Bioscience Reports, Vol. 13, No. 4, 1993
COMMEN TAR Y
The History of Proton-Driven ATP
Formation
R . J. P . W i l l i a m s ~
Received January 29, 1993; accepted March 15, 1993
This article sets down the beginnings of some thoughts in bio-energetics. It illustrates how difficult it is
in science as elsewhere to know how a new idea is generated. The literature needs very careful
examination and separation from personalities.
INTRODUCTION
In seeking to write any history there are some imperative rules. The facts must be
established as far as is possible. There is then circumstantial evidence to be
sought. At this stage it is essential that the writer does not have a theme in mind,
otherwise bias is inevitable. Once the historian is sure of his ground, within
reason, he is entitled to embellish his knowledge with a story but while his facts
should not be wrong he must expect his story to be challenged. History is elusive
and open to interpretation. I wish to give here my version of the development of
ideas concerning proton-driven A T P formation. I do this since I believe that some
of the account given by Weber in this journal (1) cannot be allowed to stand
without question, Again the history of the credit for the ideas as given briefly by
Nicholls and Ferguson (2) are not acceptable to me. Facts have been missed and
some of the credits given can therefore be called in question. I must add
immediately that both Ferguson and W e b e r have been totally helpful to me and I
do not fault them. I do believe that they have been misled by the way of some of
the early papers on this topic were written (3, 4) and that they could not have
been aware of some circumstances.
A further word needs to be said about facts. The law of libel concerns the
publication of material likely to be detrimental to the character of some person. It
is not part of this law that what is said is proven to be true. In fact the truth can
very well be libellous. I have not been able to tell the full story of my involvement
with Dr. P. Mitchell during the development of the ideas on proton-driven
ATP-formation since on two occasions I have been told by publishers that
material now included here might be libellous (5). This remained so while
Mitchell was alive and this account might never have been published if I had died
J University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, UK.
191
(H44-8463/93/(1800-0191507.00/09 1993 Plenum Publishing Corporation
Williams
192
first. On the second occasion the publishing editor stated directly that Dr.
Mitchell refused to say that he would not take out a libel action if my material
were published. I have letters to that effect. Out of courtesy I had sent my article
to Mitchell before publication so that he knew of my complaints, my willingness
to limit hurt and my intent. I believe that all I now write is at least a fair
interpretation of history and that the facts are truthful. Throughout this article I
have checked with Dr. B. Weber, who has been extremely helpful, all of those
points stated here to be historically factual. Obviously different interpretations
remain possible. I have tried to generate the most reasonable point of view.
THE BASIC IDEAS
The basic accepted ideas today behind proton-driven ATP-formation are that
(1) During oxidation of citric acid cycle intermediates by mitochondria or
during the absorption of light by chloroplasts the energy of these chemical and
physical processes appears first as charge separation.
(2) The charge separation becomes a proton chemical potential gradient.
(3) The proton gradient interacts with a reversible ATP-ase to make it an
ATP-synthetase.
The questions that are posed are then the origins of the following ideas (a)
and (b) and the connecting mechanims (c) to (e).
(a) The use of the proton as an intermediate. The charge separation had
previously been followed by many workers as electron flow, see below.
(b) The use of space in vectorial coupling
(c) The mechanism and path of electron movement
(d) The mechanism and path of proton movement
(e) The way ATP is formed.
Credit is given to Mitchell for providing the basic ideas and mechanistic solutions
in both Nicholls and Ferguson's book (2) and to some degree in Weber's article
(1). I shall take exception to these suggestions which have persisted for thirty
years for reasons which I shall now develop.
It is clear that the first authors to write the sequence of vectorial reactions (1)
to (3) incorporating the ideas (a) and (b) were Davies and Krebs in 1952 (6). It
happened that I did not see this paper, for the simple reason that I did not read
all that much of the literature of biochemistry at the time 1956-60 when I was
thinking about the problems from the point of view of an (inorganic) chemist.
The above ideas (1)-(3) were next published by me in two refereed papers in
The Enzymes 1959 (7) and in my full article in J. Theoretical Biology in January
1961 submitted August 7th 1960 (8). These papers have priority over any papers
submitted in 1961. However a basic set of ideas (1) to (3) does not provide
mechanisms connecting the initial energy producing activities and the formation
of ATP and is therefore a hypothesis without thoroughly testable connections.
Several extra features are required to build a coherent theory of reaction as given
above (c) to (e). It does not appear that Davies and Krebs ever really concerned
themselves with these mechanistic problems. My solutions in 1960 (8) were as
follows.
The Historyof Proton-Driven ATP Formation
193
Opposite (c). Electrons dropped down a potential gradient away from the
site of proton/electron separation using series of metal ions spaced -15/k apart.
This was based on much experimental evidence by myself on model systems and
by the major groups of people in the field, see below.
Opposite (d). The structure of the redox chain proteins and ATP synthetase
were such that the protons reached the synthetase before they could reach the
release point of the electron. A path of spatially diffusion restricted reactions i.e.
w~ctorial sequence in space was described. The evidence was that both units were
associated in particulate or membrane form. (Note vectorial systems were
well-known in physiology).
Opposite (e). The proton which was locally of high acidity removed water
from the reaction
ADP + Pi---->ATP + H20
In other words the reaction was dragged forward by stabilising water within
the enzyme system and it was of no consequence whether a membrane was
involved or not. There was no evidence for this mechanism. Of course the status
of these points is that of a connected set of ideas only backed in part by
experiment. Scientific facts are established by experiment but I am concerned
here at first with the development of the ideas.
In 1961 Mitchell published three papers which are the basis of ideas on ATP
production now called chemiosmotic. One is an unrefereed conference paper
from a meeting in Stockholm, September 1960, but the date of submission of the
final manuscript is unknown. Mitchell himself did not recall when it was
submitted, letter to RJPW, but Ernster (personal communication to Weber) has
indicated that it was submitted within a few days of the meeting. It was published
in late 1961 (9). The second is an unrefereed communication to the Biochemical
Transactions submitted February 15th 1961 (3) and the third paper is to Nature
submitted around April 1961 (4). These papers do not refer to any publications
either of Davies and Krebs (6) or myself (7, 8) or to the work of Crane (10) (see
below). Neither do they mention that during the period of review or writing of all
these papers Mitchell was asking for assistance from me in order to understand
my views of proton driven ATP formation (see below). We may never know for
certain what Mitchell read and when but it is clear that he failed to give reference
to several priority papers and discussion known to him before he published.
I consider that it is Mitchell's failure to refer to earlier literature, to state
clearly the origins of ideas he uses and his avoidance of reference to exchanges of
information by correspondence with others that have confused both Nicholls and
Ferguson (2) and Weber (1) amongst others in their histories of the subject
matter of proton driven ATP-formation. There was always the possiblity as far as
the literature is concerned that these omissions by Mitchell were accidental
w]hence the work of myself and Mitchell could be called coincidental (see Weber
(1)). However the facts presented below, that Mitchell at these and subsequent
times persisted in refusing to reference the work of others and later added
mis-interpretation of some features, makes this explanation improbable. To
establish the facts I need to give a full history, now and then referring to Weber's
article (1) and remarks in order to clarify points.
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Williams
BEFORE MY ACCOUNT BEGINS (1950-1958)
The problem facing the main experimentalists tackling oxidative phosphorylation, Slater, Racker, Lehninger, Green, Ernster and Chance in the
1950-1960 period was extremely tricky chemically (11). They generated all the
experimental material and much thought which lies behind the future of ideas
after 1958. I was known to several of them and I read their works but not those of
Mitchell. It is difficult to see relevance to energy transduction in Mitchell's
writings at that time and he was virtually unknown to those in the field. In fact it
is clear that in 1956 (12) and still in September (1960) (13) he believed that
oxidative chains acted in the transport of citric acid cycle compounds.
The first point to establish is the more detailed requirement which any
explanation of the bio-energetic systems of mitochondria and chloroplasts had to
provide. It was and is a link between three separate (note emphasis)
oxidation/reduction reactions and the production of ATP from ADP and P~ in
mitochondria. It was known that the oxidation/reduction reactions were in
electron transfer chains and that the chain from NADH to O2 of mitochondria
produced three ATP from three separate redox steps. Charge separation was well
documented (11). In chloroplasts there was one of these steps, effectively the
central one, not linked directly to the absorption of light. The situation was
relatively well defined in 1958 and it is easy to see interests at that time. Research
was dominated by a search for a way to energise phosphate, Pi, so as to form
ATP. The energised state was thought to be an intermediate written - P (11).
I was involved experimentally in the study of metal ion biochemistry through
examination of model inorganic complexes at that time. Of importance for the
further understanding are the following of my papers which deal with the
relationship between models and biological systems. I give these papers to
indicate that I was an experimentalist looking for fundamental molecular effects
behind the problems.
(1) An appreciation of the states of metal ions in the bioenergetic redox chains.
i.e. their spin states and open-sided character since this made it clear what
they could do, e.g. electron-transfer or/and Oz-binding. Many sites could do
no chemistry except electron transfer (7).
(2) A basic set of thoughts concerning spin-state equilibria and conformations (14).
(3) The linking of spin-state changes to protein conformational change which was
mainly occurring on oxygen-binding (15-17).
(4) A knowledge of which electron transfer reactions generate protons (7).
(5) Insight into two electron reactions of organic molecules (7, 8).
Here notice that some couples cannot do more than transfer electrons e.g.
cytochromes b, c and a while others can do two electron reactions NAD, Flavin,
Q and a3.Oz and can be connected to proton generation directly--see (7). It is
essential to see this clearly for the development of any proton coupling theory
and that this coupling has to occur three times--the cross-overs of Chance, Slater
and others in mitochondria (11).
(6) I had come to appreciate also that the passage of ions through membranes
was selective and could be restricted. Thus diffusion control as well as
The History of Proton-Driven ATP Formation
195
thermodynamic redox forces played a part in my research. The differences
here between myself and Mitchell can be seen in the papers given at a
Faraday Society meeting in 1956, where unwittingly the protagonists in this
story must have seen and heard one another for the first time (12, 18).
There are many papers up to 1958 dealing with aspects of membrane energetics
bat the fundaments of bio-energetic coupling as we see them now were unknown.
MY A C C O U N T AFTER 1958
By 1958 therefore I was aware, mostly through reading, of the central
problem of bio-energetic coupling as stated above and I wrote a review paper in
The Enzymes (7) which contains the explicit suggestion that the H / H + system
links redox reactions and ATP formation. I quote. "We further consider that the
intermediate transport along the chain of catalysis.
Substrate--~ DPN---~ Flavo protein--+ Cyt b---~ Cyt c---~Cyt a---~Cyt a 3 . O 2
is carried out by the transport of H atoms. This is certainly the case from
substrate to DPN to flavoprotein. These steps carry out oxidative phosphorylation
in common with the later steps. A reasonable postulate is that the common result
of the different steps goes through a common mechanism. Transport by hydrogen
is likely to be rapid; it is easily combined with electron transport across
cytochrome molecules, for at the periphery of both the porphyrin and imidazole
units there are readily activated hydrogen atoms; and in its oxidised state
hydrogen as the proton can bring about condensation polymerization such as
polyphosphate formation".
I believed that within its context this was the first indication that the link
between oxidation and phosphorylation is due to the switch from protonindependent redox reactions in the membrane, electron transport, to proton
dependent redox reactions of organic molecules still in association with the
membrane. Control of diffusion of the acidity in a proton channel then drove the
proton to the site of ATP formation, equally from all three sites. In fact it was
predated by Davies and Krebs (6).
Now this review did not solve the bio-energetic problem but posed it in a
new form while breaking it down to
(1) The reducing equivalents were in the form of H, i.e. from NADH, FADH or
QH2 i.e. two electron steps at two places in the chain of mitochondria and
one place in the chloroplast chain but in the form of electrons i.e. one
electron couples in a variety of iron, haem iron and copper proteins. This
step in my description was not really unorthodox but was far from
conventional.
(2) The reaction of dioxygen which could only be at cytochrome a3 was described
as being like that of haemoglobin and reduction here by electrons produced
OH-. Again a somewhat orthodox position but cytochrome a 3 was likened to
haemoglobin in its spin states (14). Note the association with pH change and
a further two electron step.
196
Williams
(3) All three steps of mitchondria and later the steps of chloroplasts were said to
produce protons but no precise description of the whereabouts of the protons
was given. This proved to be a central problem. No other intermediates were
mentioned or required since
(4) It was stated that protons can drive condensation reactions. But this again
was a statement of a way A T P could be formed. However it was implicit that
this could only occur if the protons retained the energy of the redox reaction.
Steps (3) and (4) were quite new to the field at that time.
Clearly to solve the problem a more coherent treatment was necessary and
there were several obvious points to analyse. (1) How do electrons move about
over say 50 A in biological systems so as to create an energised proton gradient in
space? (2) How do protons move about in biological systems? and (3) H o w can
ATP be formed from A D P and Pi using protons and nothing else? The insistence
on the last step comes from the point that four A T P synthetic steps had to have a
common intermediate. Clearly chains of catalysts are required.
Weber states that I made no attempt to analyse these questions of oxidative
phosphorylation by experiment (1). The truth is that I had already by 1961 spent
much experimental effort on electron transfer (7), on 02 reactions with haem
iron, including the generation of ideas on cooperativity (17), and some on
photochemistry. I shall show below that in fact I have spent continuously some 35
years tackling the molecular problems I believe to be central to these mechanisms. It is the case that Weber (1) does not and to some degree Mitchell (35)
never does describe them as chemical molecular problems but they engage
themselves with physiological description of fields. It was also necessary for me to
develop a coherent account of the proton driven A T P formation. By invitation of
Prof. Danielli (see Weber's account) I submitted a manuscript to J. Theoretical
Biology, received August 7th 1960 (8). It had taken me some two years of
thought to work out a scheme in which I believed. Let me explain the difficulties.
(1) There was no strong reason to believe that electrons could jump long
distances. The only protein structures known were myoglobin and haemoglobin. The haem was buried but reducible. My view was that if the electron
movement was to be connected to protons and then the protons used
separately there had to be a movement of e and H + over some distance away
from one another since they must not recombine nor must the products O H and H + recombine until A T P had formed. I had to study long-range electron
transfer in materials where protons could not follow in depth. I have done so
for some forty years from 1954, see (14, 19, 20).
(2) How could protons be used in buffered solutions? A biological cytoplasm has
a high buffer capacity. Buffers must waste energy.
(3) Why would the proton not just diffuse and be diluted? This could destroy the
energy of the proton necessary to make A T P at least until a lot of capacity
had been built up. I had to study proton activation in different media. I have
done so for 25 years in molecular systems. By 1975 we had shown how proton
channels could be made from a helical peptide, alamethicin (21, 22) in a
membrane.
(4) How could a proton make A T P from A D P and Pi? This is far from obvious
Tile History of Proton-Driven ATP Formation
197
and is not totally solved yet. I had studied condensation polymerisation of
which this is but an example (23). I chose later (1973-) to model the
reactions on accessible materials--kinases--which I have studied for 20 years
(21, 24). With Boyer (25) I came to believe in conformationally driven
reactions (26).
A scheme was completed and published January 1961, which gave evidence for
(5) Electrons hopped some 10-15 A from site to site leaving protons behind. This
fitted the schemes of Chance and Slater amongst others (11).
(6) Protons avoided the bulk aqueous phases and remained in close association
with the particles for redox reaction. This required a diffusion path for
protons and no other ions. Such paths were known in other materials, I
stated specifically that the bulk aqueous phases could be used for proton flow
but this was not the best device (8). (N.B. This is chemiosmosis).
(7') The proton could make A T P only in a manner which to my knowledge
nobody had suggested before. The reaction is
A D P + Pi--~ A T P + H 2 0
However biochemists did not consider that removal of water could solve the
thermodynamic problem. They wrote the reaction just as A D P + P~--* ATP.
More obvious choices were to stabilise A T P or to destabilise Pi ( - P ) or A D P
rather than to stabilise H20. It still is so. However a proton cannot stabilise
A T P nor can it destabilise Pi or A D P directly in a non-aqueous phase. I
concluded that it should be used to remove H 2 0 but this can only be done if
H + does not remain in the bulk aqueous phase. The idea was that in some
local trapped enzymic environment the water was sucked out from the
ATPase by the proton. This was and is a most unusual approach to A T P
formation. (In this form it is not correct, but see later).
It is a fact that in virtually all these respects there is no prior literature and it
is and was incumbent on those writing subsequently that they gave references.
Only on this assumption can trust be built, so that we can exchange ideas freely.
I hope I have made it clear why, although I had considered chemiosmosis as
far as bulk protons were concerned, I rejected it. There is (1) the problem of
buffer capacity (2) the problem of the diffusion path. Both made a local path
more efficient. I made the points time and again over the years but I insist that I
did describe what is called chemiosmosis in this paper. After describing in the
paper (8) an electro-chemical cell without transference I write (p. 3/4) " T h e
effect of a salt bridge (a kind of membrane) is to prevent the coming together of
some of the species H + and X - which would otherwise react . . . . In some
biological systems such a situation is realised. H o w e v e r restriction of diffusion by
a salt bridge or a membrane is unnecessary and reactivity can be controlled by
catalysts. They can be made to react by suitably placed catalysts before they can
diffuse to one another although diffusion itself need not be restricted." It is also
clear that the control of space envisaged all the time is a vectorial energy control
along a diffusion path. (I believe that this path is the best to this day and that
biology uses it before it reaches the steady state, which has become called
chemiosmotic).
198
Williams
I must make it absolutely clear that I had told Mitchell again in a letter
March 5th 1961 how chemiosmosis might work. I had no indication of his interest
at that time. I prove this by the following quotation from the second letter to
Mitchell, March 5th 1961. Remember to my knowledge and from his writings to
me he had never shown anything but interest in my schemes. He claimed none of
his own. (The letters will be published in full by Dr. B. Weber).
"I hold the view that a phosphorylating system is not in equilibrium with
regard to the hydrogen ion concentration. On admitting oxygen to the cytochrome chain system in mitochondria the measurable pH can only refer to the
bulk pH, i.e. in the vessel which contains the fluid in which the mitochondria are
suspended. I wish to think about two regions of the mitochondria which are well
separated in space. The region near the initial attack of oxygen--i.e, near cyt.
oxidase. Here we would all agree we have the reaction O2 + 2H20 + 4e--+ 4OH-.
The electrons are transported from the end of the cytochrome chain where we
have the reaction RH--* H + + e. In a system where electron transport is faster
than hydrogen ion diffusion then there will be a rise in 'pH' near cytochrome
oxidase and a fall near the terminal hydrogen carrier. The changes in 'pH' can be
just as large as the redox potential difference between the couples in the two
regions when the system would come into an equilibrium like that in a cell
without transference. This would imply complete restriction of hydrogen and
hydroxyl ion transport. One way of achieving this is to invent a membrane which
is permeable to all sorts of materials such as water, carbon dioxide, and organic
molecules but not to hydrogen. I cannot visualise this easily but if one can, then
the 'pH' can take on its ordinary meaning in the different separate space
compartments."
and by quoting my second paper (27) (Received April 5th 1961. Revised 21
December 1961) again written without any knowledge of any of Mitchell's
subsequent publications.
"Now a biological system is split into many compartments by what biologists
for their convenience have called "membranes". These membranes in mitochondria hold the essential catalysts of the electron transfer chain and carry out the
process of oxidative phsophorylation. The membrane is not a simple dividing
barrier between separate parts of space (this is the conventional physical chemical
model) but is a restricted, independent, largely lipid, phase. It is the reactions in
this phase which we are discussing for in it the protons are generated. (N.B. This
is now in 1993 known to be true (41-44)). While oxidative phosphorylation is in
progres s the phase is not in thermodynamic equilibrium with the phases in contact
with it and thus the activities of any of the components in the phase cannot be
deduced from the analytical concentrations (gram moles/litre) of these components in neighbouring phases. Nor are their equilibrium quotients or relativefree energies in these phases valid in the lipid phase. It is a familiar observation in
the study of the partition of an organic acid between an aqueous and an organic
phase that equilibrium is slowly established. Before equilibrium is established the
"pH" or other "activities" of the two phases are not the same. Here the
The Historyof Proton-Driven ATP Formation
199
definition of pH must be (a) in the aqueous phase; that measured by conventional
methods in the aqueous phase; and (b) in the organic, lipid, phase; that which
would be measured in an aqueous phase of infinitesimal capacity if the organic
plhase could be brought instantaneously into equilibrium with it. Now the
problem of pH in mitochondria is exactly like this. In mitochondria systems there
are two similar, but far from identical, aqueous phases separated by the
"membrane" phase. We would suggest that during oxidative phosphorylation pH
equilibrium cannot be established between these phases and that hydrogen ions
generated at a high equivalent aqueous activity inside the membrane phase
diffuse but slowly through the membrane phase to the outside. This is because
they combine with anions generated in the organic phase. In this way kinetically
stable but thermodynamically unstable compounds, R-OH, are generated in the
membrane at a high activity and after particular processing, condensation, are
passed out into the aqueous medium for further transformations. Reaction (6) is
of this kind. Energy-rich phosphorylated compounds are generated in a partly
lipid phase--that of the mitochondrial membrane--at a nominal low pH". (Note.
As a driving force the second aqueous phase is of no consequence).
The first paper was published in January 1961 and was available to all editors
of the Journal late in that month or early February 1961. Academic Press state
that the journal was first sent out in January 1961 (letter to RJPW). The
controlling editor of the Journal was Prof. J.F. Danielli and one of the editors
was his pupil Dr. P. Mitchell. There has always been the possibility that Mitchell
refereed this paper in August 1960. I make this remark because of a statement by
Weber "Nor did Mitchell have access to Williams' manuscript as a referee prior
to publication (James Danielli, 2 March, 1982)" (1). I have copies of two letters
from Danielli to myself, on 14th July and 4th October 1979. In these letters
Danielli states that he does not know who refereed my papers and that all records
were destroyed every 3 years. Thus Danielli's replies are contradictory. This
underlying suspicion would not exist of course but for the fact that Mitchell had
every opportunity of referring to earlier publications than his own but did not do
so, when he came to publish later.
I trust that the reader will see that by the beginning of August 1960 and again
in early 1961 I considered that I had developed a coherent theoretical structure of
proton driven ATP formation partly backed by experiment and that at that time
there were no communications or publications by Mitchell which concerned the
problems. Even so I acknowledged in April 1961 (27) that I had corresponded
with Mitchell in extenso but I deliberately state that he is not party to my views. I
had no knowledge when I wrote the paper that he was. I was concerned to show
how cytochrome oxidase could do the same trick as particles I and II, i.e. to
generate protons.
There is another curious feature. Late in 1959 I had shown the precursor of
my paper (8) to Prof. Krebs and asked for an opinion. He wrote saying that he
did not think such hypotheses should be published. I would have sent it to the
Biochemical Journal but for the later invitation to write for J. Theoretical
Biology, where it was lost from view. In writing to me Krebs did not mention his
earlier paper with Davies (6) which had outlined chemiosmosis. I have to
conclude that Davies was largely the influence behind their paper.
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Williams
T H E H I S T O R Y OF MITCHELL'S W O R K
Let us now turn to Mitchell. H e had continued work, which is of
considerable interest in itself, on chemiosmosis from 1950-1960 but which had
nothing to do with the above bio-energetics. In August 1960 he was at a meeting
in Prague and in his paper (28) he had added no comments of interest on proton
coupling to A T P formation to this analysis of substrate transport. This is not to
say that he had no interest in acid gradients but this subject has a disconnected
long history in physiology. The discussion in Prague is limited to transport and its
possible connection to metabolism. Mitchell's ideas on these couplings in Prague
are of great value and it is a pity that I had not seen them. He was not alone in
his thinking on coupled reactions however and he refers to many descriptions of
the work of others. I have no doubt about the quality of all this work. At that
meeting there was one contribution which gave a solution to chemiosmotic
transport coupling and it is that of Crane (10).
At the Prague meeting Crane solved a different coupling p r o b l e m - - t h a t of
the transport of sugars into cells. The coupling is by the chemiosmotic mechanism
using the Na § gradient from ATP-hydrolysis. Crane's account of his interaction
with Mitchell at this meeting is published (10). There can be little doubt that this
paper helped Mitchell in the writing of his later paper at the Stockholm meeting
to which I refer next but it is not referenced. Why? Notice Crane connected
correctly for the first time a membrane enzyme reaction to transport of organic
molecules via couplings, Na § ions and sugars, but he kept the - P notation of
chemical intermediates (10). Strangely Mitchell (4) does not follow him in 1961 in
that he does not move ions through membranes except by exchange. The
problems which have really bothered me for so long, and to which W e b e r alludes
(1), can be said to begin in Mitchell's next paper.
At a Stockholm meeting in September 1960 Mitchell proposes directly a
different enzyme coupling of sugar phosphate formation and proton gradients (9).
This is based on protons which do not cross membranes(!) and on a dehydration
mechanism by a proton field driven suction. The dehydration is described in
exactly the thermodynamic language I use in my paper submitted August 1960
(8). All of this proposal is now known to be incorect. At the same time he states
in one line that he sees that A T P can be made by such gradients which mirrors
my remarks in 1959 (7). There is no advance here even from Davies and Krebs
(6), about whose work he knows (28, 35). There can be no question of priority of
ideas in this paper which was only published in late 1961. Unfortunately as Weber
points out there is a question of a different kind. We have to ask again: had
Mitchell knowledge of Williams' paper which had been submitted to Danielli on
August 5th? We shall never know the answer to the question as I shall show. Why
in fact do Weber and I raise this ghost? It is Mitchell's subsequent actions which
leave him suspect always. The reasons are partly scientific in that the suggestions
have sprung in some sense de n o v o and have two major features which I also
developed before him (1) It uses a proton as the intermediate in a spatially
controlled vector system and (2) it removes water from sugar phosphates by this
proton. The appearance of the second is equally puzzling to me as the first. It
The Historyof Proton-Driven ATP Formation
201
took me a long time to worry this out as I show in my 1960 article, and it is
wrong!
It is clear that Mitchell did not develop his ideas from the way that
uncouplers work through proton transport as Weber (1) suggests since at the
meeting in Sept. 1960 he describes dinitrophenol (DNP) as acting as a simple
blocker of succinate dehydrogenase (13). Thus Mitchell's views do not originate
fi~om ideas concerning uncoupling. Again the novel views of dehydration of
phosphate in the formation of phosphate esters are not described in a doctorate
thesis submitted by Mitchell's pupil, B. P. Stephen (29) 1960 at Edinburgh
University. A thorough search of the Mitchell archives at Bodmin is necessary for
us to know what he was doing. This will be done by Dr. B. Weber.
Mitchell according to Weber (1) next submits a communication (no referees)
to the Biochemical Society on February 15th (published in Proceedings of the
Biochemical Society (3), which is almost certainly after the time when he had
read my paper in J. Theoret Biology, circulated to editors in January 1961. He
does not give any references to this paper (8), my paper in the Enzymes (7), to
Davies and Krebs (6) or to Crane (10). It refers directly to chemiosmosis and
energy coupling, uses the same dehydration mechanism by fields, and protons do
not cross the ATP-ase or the membrane.
On February 24th Mitchell wrote the following letter to me. I quote in
full.
Chemical Biology Unit
Zoology Department
West Mains Road
Edinburgh 9
Dr. R. J. P Williams
Wadham College
Oxford
England
24th February 1961
Dear Dr. Williams
I was interested to see your recent paper on "Possible Functions of
Chains of Catalysts" in the Journal of Theoretical Biology and especially in
your conception of "dislocated reactions"; and I am writing to ask if you
would be so kind as to clarify one or two points to help me to understand
your conception in relation to the current biochemical views on the
organisation of multi-enzyme systems.
As I understand it, your view is that the multiplicity of catalysts is
required to "dislocate" chemical reactions, or in other words to allow the
reactions to occur at separate points in space regarded as microscopic
effectively homogeneous phases in which the appropriate catalysts can speed
up the "required" reaction. It is in this light that you suggest that the
reaction
H + + ADP + P-+ ATP
202
Williams
can be brought about by raising the proton concentration in a dilocated
phase in which an ATPase is situated, this reaction being thermodynamically
favourable at low pH. Similarly you suggest that the reaction
Sugar + ATP---~ A D P + sugarphosphate + H §
can be driven forward by raising the O H ' concentration in the phase in which
this reaction occurs and thus lowering [H§
the product [ H § 2 1 OH]
5
being
constant.
Have I got this right?
When you speak of the high local concentration of a chemical--of
protons, for e x a m p l e - - d o you mean the activity in the thermodynamic
sense? In other words are you referring to a concentration of effectively free
particles of a given chemical species? There seemed to be hardly a shadow of
doubt as to whether this was what you meant, but I wondered about it
because you say that the utilisation of space in multienzyme systems removes
the necessity for postulating semi-permeable membranes in many biological
systems. I wondered why the particles--such as p r o t o n s - - should not escape
from the "dislocated" sites extremely fast and irreversibly if they were not, in
fact, bound in some way at the sites of the "dislocated" reactions.
I hope you will not find these questions too much of a nuisance, and I
look forward to hearing from you.
Yours sincerely,
Peter Mitchell
P.S. I am writing a review on the organisation of enzyme-systems and this is
partly why I would like to make sure that I have got your conception right.
Today I have to ask, Is this letter one you would expect from a man who has just
submitted a communication and has a line in press on exactly the topic of my
paper? At best the P.S. is untrue and deceitful. He is wanting to have my opinion
for a review he is writing. That is all?
But worse is to follow. I wrote to him explaining my views on proton
energetics on February 27th and on March 2nd he writes again with gentlemanly
enquiries. On March 5th I point out to him that he has made a muddle of my
thinking and then I explain my views in full including chemiosmosis as recorded
above, (see p. 12).
It has to be very clear that in the early correspondence Mitchell at no time
suggested that he himself had any thoughts on any subject concerning any topic
on bio-energetics. He made gentlemanly enquiries and criticisms of my constructions. In the fullness of time this correspondence will be published by Dr. B.
Weber. The Royal Society has copies. I could have had no other view than that I
was explaining to Mitchell points in science as I saw them.
In the next letters he changes his tone and begins to say he has ideas of his
own which are not really developed. I become very suspicious of all this. At least
it is devious and at worst--what is going on? He tells me of his paper at
Stockholm (9) but not of the paper in Biochem J. (3) or that he is actually writing
The History of Proton-Driven ATP Formation
203
the article about to b e submitted to Nature (4), which has no references to
priority papers.
Before I terminated the exchange by saying I do not wish him to quote my
letters Mitchell admits he has also read my paper in The Enzymes some time
before (Mitchell to Williams letter of March 15th 1961). I told Mitchell I was
writing a second paper in which explicitly I thank him for the exchange, saying it
has been helpful (p. 222 of (27)). In contrast Mitchell told me nothing of his
papers none of which cross refer to me in any way and none of which had reached
proof stage by April 1961. There are almost no references to my work in his
writings to this day. Why?
I first became aware of Mitchell's paper (4) on bio-energetics on return from
holiday in late August 1961. I found reference (30) much later. I was never more
put out in my life. I did not and still do not understand what motivated him. One
of the papers he published in 1961 (30), there were four, was even given in
Oxford while I was there without my knowledge. I knew nothing about it since I
was not a member of the Biochemical Society.
There is in fact something very odd about the Mitchell proposals on
chemiosmosis in 1961. The mechanism is as improbable as cold fusion at room
temperature. Mitchell pulis water to pieces with an electric field. H e does not let
protons cross the membrane. This is a gross mistake but it is the only way in
which he can couple an osmotic gradient to a chemical reaction if he keeps to his
osmotic approach. Every chemist knew it could not work. This idea had to go
since he could not let the protons enter the membrane or our ideas would have
been identical. [Note the osmotic gradient is used to remove H 2 0 but this is not
necessary for him but he uses exactly the thermodynamic argument for this novel
step already given by me (8) and repeated to him in letters for doing the
re,action]. W h y did he do this? The answer must be that he really had no way of
making ATP. Notice too that he uses anhydrous H + and O H - in removing water
from the membrane but later claims that I introduce such "nonsense", see Weber
(1). Again why does he write in this misleading way? Also notice he does not
follow Crane by moving protons across membranes until much later (1966) (31).
There is no point in denying virtue. The good new features of Mitchell's
work are
(1) the use of membrane potentials. (Here let it be r e m e m b e r e d that I had
(18) and have since 1961 worked in this field (32) and have never found it easy to
separate the potential in the bulk phase and the potential of bound charges in or
on membranes. I do not know with confidence how to do this today).
(2) The protons he refers to as giving a p H gradient are measurable. Finding
them does not constitute a mechanism but only one of a chain of intermediates as
we shall see. However he forces attention upon an easily measurable proton
gradient and sets out later to measure it.
(3) H e is led to thoughts about ion exchanges across membranes which prove
to be very productive.
(4) H e is led later to consider uncouplers as proton transfer agents (Note this
would work for the "local" model too and there is a further alternative way of
thinking about the pKa d e p e n d e n c e - - s e e (27)--which was not eliminated by the
early experiments).
204
Williams
In 1961 I had written my second paper (27) since I was worried about two
things. The first is the cytochrome axidase step. There are no proton carriers in
the step! It is cytochrome c electrons plus O2--+2OH-. Where do the protons
come from? I used the O H - as the remote sink for protons from other sources
after ATP was made since the excellent experimental work of Chance, Slater,
Racker, Lehninger and others (11) (forget mistaken quarrels about phosphorylated intermediates) had proved that this last reaction of the mitochondrial chain
does give ATP. How? I invent a possibility which is wrong. The second problem
is the diffusion of the proton. I indicate that it could go through a channel in any
membrane structure (see the quotation on page 13). Later I give pictures of this
scheme and contrast it with Mitchell's views of the same time, i.e. field driven
reactions.
Now by 1966 Mitchell had changed his scheme and does exactly this: he
passes protons through a channel in the membrane to do the ATP synthesis (31).
In this privately produced book (31) he again does not refer to J. Theoret. Biol.
(8, 27) in which I give this as a way in which to handle chemiosmosis! (N.B.
without reference to Mitchell since I have not seen a Mitchell paper). I write to
protest. He replies as if he is the offended person. It is this 1966 paper which
Nicholls and Ferguson (2) use for the history of all the ideas!
E X C H A N G E AFTER 1961
My views in the period 1961-1975 were not unknown as is suggested by
Weber (1). I had lectured in Slater's and Chance's laboratories by invitation
in the 1960's and by 1975 I had attended two symposia in Bari (21, 26). I opened
the one in 1970 (26), and I had given lectures elsewhere plus one at New York
Academy of Sciences Meeting 1974 (33). I was awarded the Keilin Medal of the
Biochemical Society in 1974 and my lecture describes these matters.
The Bari Meetings give an immediate feel for the period 1970-75. They also
show that we all saw the similarities in the views of Mitchell and myself which are
incorrectly described by Weber as quite distinct (1). I quote from the discussion
at the first Bari conference in 1970 (34).
DISCUSSION COMMENTS
P. MITCHELL
The Chair wishes me to respond to Dr. Williams. I think he has rightly
been stressing the important point that whatever happens between the
hydrodehydration and the oxidoreduction reactions, there must be some
coupling process that causes them to be mutually dependent.
Of course, each set of reactions--the hydrodehydration and the
oxidoreduction--must go according to valid chemical principles. The fundamental question is: Are the sites of interaction between the flows through
The Historyof Proton-DrivenATP Formation
205
the oxidoreduction and hydrodehydration systems of molecular dimensions-which he would like them to be to keep the protons confined in the lipids--or
are these sites of interaction much more extensive, the oxidoreduction and
hydrodehydration systems being separate chemically and physically, the
coupling between them being accomplished by the flow of protons down
electrochemical gradients across the coupling membrane in which the two
systems separately reside? I think that Dr. Williams staged the position in a
slightly different way, but we agree about the fundamental problem.
Coupling at the chemical level of dimensions must involve chemical
intermediates that are common to the oxidoreduction and hydrodehydration
systems, or must involve corresponding chemical complexes or conformational states in domains of chemical dimensions, whereas chemiosmotic
coupling of the type that I have described does not require the interaction
between hydrodehydration and oxidoreduction should occur directly at the
molecular level of dimensions, but only indirectly via the flow of protons. It
follows that the chemical complexities that the proponents of the chemical
coupling hypothesis, or of Dr. Williams' modifications of that hypothesis,
have found themselves obliged to invoke to explain the coupling phenomena,
have tended to be considerably greater and more vague than those required
by my hypothesis. I agree with Dr. Williams, however, that the same basic
chemical principles must apply in any case. The main difference--and we
must not underrate its importance--between the alternative types of hypotheses of the coupling mechanism is concerned with the distance over which
coupling between oxidoreduction and hydrodehydration is transmitted, and
the consequent degree of physical and chemical independence between the
two systems.
P. D. BOYER
In one sense some of the views advanced by Dr. Mitchell on a proton
gradient across the membrane, and the view expressed by Dr. Williams of a
localized proton may represent two extremes of a gradient situation. Thus, if
we confine the proton to the membrane structure, it may become more and
more localized as it has access to less water. I concur with Dr. Williams that
a proton produced at an electron-transfer site in the absence of water would
make an effective dehydrating agent. I wonder if he has given consideration
to the smallest volume of water in which you would need to utilized 1 H + to
make 1 ATP. For example, will 1 proton for every 55 water molecules, about
equivalent to an 1-N solution, suffice?
R. J. P. WILLIAMS
The calculations referred to by Dr. Boyer were made by me in an article
in J. Theoret. Biol. t, and referred to again in that same journal z. Given that
the energy that is required for oxidative phosphorylation is about 10 kcal
then a 1-N solution is about correct. However, all such calculations are based
upon the definition of the aqueous standard states which will hardly be
206
WilLiams
relevant in a m e m b r a n e . If I may m a k e the point again, and referring to your
first comment, it is true that as the proton becomes m o r e and m o r e localized
then the proton-gradient hypothesis becomes the same as the chemicalintermediate hypothesis.
REFERENCES
1. Williams, R. J. P. (1961) J. Theoret. Biol., 1, 1.
2. Williams, R. J. P. (1962). J. Theoret. Biol., 3, 209.
A. R. CROFTS
The mechanism for phosphorylation by a localized proton you have
proposed can account for the final equilibrium of phosphorylation. H o w e v e r ,
net phosphorplation requires a <<flow>> of water through the system. H o w
can this be a c c o m m o d a t e d in your scheme?
R. J. P. WILLIAMS
The scheme requires that water leaves the m e m b r a n e in the c o m p a n y of
a proton and, therefore, it also requires that they will enter the reaction site
without the water. To do this you need to generate the proton from a
hydrogen carrier which will undergo redox reaction. It is easy to conceive
that the hydrogen carrier is a molecule such as a hydroquinone. The
mechanism suggests a steady-state dehydration of the m e m b r a n e phase and it
therefore follows that the condition of the m e m b r a n e will undergo a
conformational modification on change of state. T h e r e is no need for a
magical asymmetric A T P a s e (see ref. 1).
REFERENCE
1. Williams, R. J. P. in Sanadi, D. R., Current Topics in Bioenergetics, Vol. 3, Academic Press,
New York, 1969, p. 79 (see p. 80).
Note I do not say here and have never said that chemiosmosis and the local
proton ideas are very different. Indeed Mitchell does not say so either. His early
work in chemiosmosis constantly refers to particles and in his work on
chemiosmosis in energy capture he refers now and then to my views as
micro-chemosmosis! (35). The fundamental differences lie only in whether or not
A T P is made under diffusion rate limiting conditions for the proton or is it
necessary to reach steady state conditions first, and whether or not the m e m b r a n e
is entered by redox protons or not i.e. do redox protons remain associated with or
enter the m e m b r a n e or are they osmotic only?
I have now to put a question to my reader. Given this background why did
Mitchell behave as he did in 1961 and subsequently? It must be agreed that it was
not excusable but there could be reasons to which different degrees of culpability
are attached.
]'he History of Proton-Driven ATP Formation
207
(a) Assume that by Feb 15th 1961--when he submitted his abstract
(3)--Mitchell had seen none of my work. (There is evidence that he had seen
Davies and Krebs (6) see Weber (1)). The only reason for writing to me in the
way he did is that he knows before the end of that month on seeing my papers
that he has been scooped. Ever after that he uses whatever procedure he can to
remove that impression, i.e. gives no references and distorts my arguments, and
in fact he succeeds. H e had a duty to refer in all his 1961 publications, there are
no others, to my articles and letters and to prior works of others.
(b) Assume that at some time after hearing Crane (August in Prague and
before the September meeting (Stockholm in 1960) he knew in outline or in detail
of my work in one or both papers (7) (8). Then not only in the Nature paper
where he gives no references deliberately (this is irrefutable) but also in all
previous writing on this topic he gives no references to Krebs and Davies (6),
Williams (8), or Crane (10), when he knows full well of these works.
In either case over many years he sets out to deceive me and the scientific
public deliberately and succeeds. Can this be denied?
THE QUESTION OF LIBEL
Sometimes people ask me why if I have this evidence I have not written it
down before. There are two reasons
(i) There is room for a certain amount of misjudgement from my position. It
involves accepting that Mitchell saw, in one month August 1960 what took me
2-3 years to develop, not one radical step but three, which, it happens, were in
the literature and which he missed. I cannot accept this but there is residual
doubt. It is Mitchell's subsequent repeated actions, refusal to give any references,
which created suspicion for both myself and Weber. There may be others in this
debate who have felt roughly treated but they must speak for themselves.
(ii) When I tried to express the worry that there might be foul play which
ought to be eliminated since there are reputations at stake, I find that I cannot
publish. The reasons concern the laws of libel.
The first incident concerns a conference in New York where I wrote a longish
footnote giving the above history (33). 1 had a nice letter from Prof. David Green
explaining the law of libel, September 17th 1973. The publishers are afraid he
said that the above account is libellous. The second is more shattering. On the
invitation of Prof. Semenza, Mitchell and I amongst others were requested to
write the history of our work. He did this with virtually no appropriate reference
to me (35). Of course I did not see this paper before it was printed. This is
supposed to be a history of personal interactions. I write fairly closely along the
lines of this present paper (5, 36). Semenza said it was fine. However J. Wiley
Press editors expressed a worry that the article was libellous. (N.B. the truth is
libellous if it is defamatory of a living person). It did not believe that Mitchell
would claim this so I sent him the manuscript offering to change it so as to reduce
offence and asking him to write saying he would not take out a libel action. He
refused to do this! (letter of 21st April 1981 to R J P W from J. Wiley) Why?
208
Williams
On this matter I had telephone conservations with Wiley editors (I have
letters to prove this) but the phone calls were not recorded. In one call it was
pointed out that for my own sake I should drop the paper and not try to publish
elsewhere. The point was made that Wiley would not risk challenging Mitchell for
reasons which I must leave to the reader's imagination. The point was also made
that the uncertainty of the law was such that if a libel action was taken
successfully against me I could be financially bankrupt. I ceased to believe that I
could publish other than hints. Do not forget that I asked Mitchell directly to let
me publish my history. I decided to place the letters and the evidence in The
Royal Society Archive. The people who have read the manuscript are Mitchell,
Semenza and the Wiley Editors, and one or two others who were told not to
quote. Semenza apologised to me while he did not blame Mitchell. The law is the
law and a man is entitled to defend his character against truths and lies almost
equally! Only now can I print my version stung into action by references (1) and
(2).
T H E SCIENTIFIC S C E N E IN 1975
With these points in mind we can return to Bari 1975 (21). It must be
remembered that almost nobody in the audience has studied protein structure in
any depth. Mitchell takes the approach given his name and continues an analysis
of bulk physiological concepts pH, ~p and so on. My talk is quite different. I
search for a pathway for electrons and protons and for a molecular mechanism for
making ATP using protons. Moreover I have now experiments to which I refer.
(1) I will use cytochrome c as an electron transfer protein to study
electron/proton coupling. This work has today come to fruition in that it
shows different local couplings of electronic energy states of a protein with
conformational states (mechanical energy) and protonation states. It allows
both proton and electron paths to be analysed (37, 38).
(2) I had found that ion transport is guided by a helical peptide, alamethicin. The
linear structure is proved by Martin and Williams (22). This allows the
postulate that the movement of protons is through channels supported by
helices. This work has been greatly extended and is now supported by much
independent data (37).
(3) The formation of ATP will be analysed in terms of the properties of kinases
and in particular phosphoglycerate kinase. This work is now completed. We
shall publish a full review shortly (39).
In other words by 1975 I had found the experimental tool I neded--it is nuclear
magnetic resonance (NMR). The methods are developed by my colleagues and
students within the Oxford Enzyme Group as well as by others. Although it has
taken 25 years to see the picture more clearly it is now emerging. NMR allows
you to follow protons which was impossible by absorption spectrophotometry the
The Historyof Proton-Driven ATP Formation
209
weapon of choice from 1950 to 1980--and to follow dynamics and statics of
proteins against the background of X-ray crystal structures.
THE PICTURE T O D A Y
This account would not be so poignant were it not for certain turns of events.
It is clear that a large body of evidence favours the overall steady state hypothesis
of chemiosmosis. Proton gradients in the steady state can equilibrate very nearly
with the ADP + P~~ ATP reaction. This is at least in part a view pointed out by
Davies and Krebs and myself before Mitchell published any paper. However
Mitchell's influence was very much greater in forcing experimentalists including
himself to examine these ideas. In itself this work does not give a mechanism of
the pathway of course. The mechanisms proposed by Mitchell in 1961 are
undoubtedly incorrect in that
(1) Electrons do not cross membranes to generate protons in aqueous
phases. They generate protonated species in the membrane first (41-44).
(2) ATP is not formed by a field driven reaction. It is formed by protons
entering the membrane and driving conformational changes, see Boyer (25) and
Williams (26). The coupling between a proton and ATP has to be in a particle
and not by osmotic coupling.
(3) It is at least doubtful if the shortest path from the generate proton to the
ATP synthetase requires the bulk phase water. This means that the steady state
proton gradients could well be back-up stores not essential intermediates.
Increasingly today a molecular picture of the apparatus in mitochondria and
thylakoids is evolving. From around 1970 I set out to substantiate the picture
slhown in Fig. 1. Points of substantial interest in the discussion are known. (1)
There is localised positioning of the proteins in both membranes following the
curvature of the membranes (40, 41). (2) The electrons from the reaction centre
of photosystem I do not cross the membrane but they reach buried coenzyme Q
and oxygen to which protons diffuse in a path in the membrane (42, 43). (3) It is
probable that diffusion of protons occurs in the membrane at the sites of Q
reactions in mitochondria. (4) It is certain that protons diffuse through the site of
cytochrome oxidase (44). (5) It is certain that protons diffuse through a channel in
the ATP-synthetase (25). (6) It is highly probable that ATP is formed by a
coupling of protons (free from water: "anhydrous?") with mechanical or conforrnational changes (25, 40, 45). I state with conviction that not one of these last
points arose through Mitchell's work. I leave the reader to form a history of
bio-energetics for himself while I look forward to the future of localised currents
(40, 44) of protons in membranes.
I have written this article to describe how I reacted when I read two accounts
of these "discoveries". I am told that others will say I am jealous. I believe I
arn more angry than jealous but would you not be both? But there is another
purpose: I hope that in the hurly-burly of rough exchanges of scientists, others
can see that we must be able to write to one another in a spirit of trust, otherwise
science becomes warfare as in the above.
210
Williams
i
"='
Glu 190
"5
HI"= 5 2
His 53
"
MEM IIRANI
BILAYER
" MEMBRANE
CIL- HELICES
P'RO?EIN
PLAN VIEW
Cl-HELICES
Fig. L The figure is an attempt to model the ATP-synthetase using the ideas
expressed in reference (21) and detailed analysis of helical proteins, e.g. alamethicin, calmodulin and colicins, and a kinase, phosphoglycerate kinase as detailed in
the references. The data would indicate that the passage of protons through a
proton wire (made of helical proteins) (21, 45) would, on binding to membrane
earboxylate groups, twist the helices so that mechanical energy was transmitted to
the hinge-region helices of the ATP synthetase causing ATP to be released. A
more detailed description is given elsewhere (37, 40). Today there is no suggestion
that the chemiosmotic field mechanism has any standing.
The History of Proton-Driven ATP Formation
211
REFERENCES
Weber, B. R. (1991) Biosci. Rep. 11:577-592.
Nicholls, D. G. and Ferguson, S. J. (1992) Bioenergeties 2, Academic Press, London, 16-18.
Mitchell, P. (1961) Biochem. J. 79:23P.
Mitchell, P. (1961) Nature 191: 144-148.
Williams, R. J. P. (1980) Article submitted for publication in Evolving Life Science ed. G.
Semenza, J. Wiley, 1980. Not published due to possibility of libellous content. See also reference
(35).
6. Davies, R. E. and Krebs, H. A. (1952) Biochem. Soc. Syrup. No. 8 77-92; see also Davies R. E.
and Ogston, A. G. (1950) Biochem. J. 46:324-333.
7. Williams, R. J. P. (1959) in: The Enzymes Vol. 1, ed. (P. Boyer, H. Lardy and H. Myrb~ick)
Academic Press 391-441.
8. Williams, R. J. P, (1961)J. Theoret. Biol. 1: 1-17.
9. Mitchell, P. (1961) in: Biological Structure and Function Vol. II (eds T. W. Goodwin and O.
Lindberg) Academic Press London 581-599.
10. Crane, P. K. (1983) in : Comprehensive Biochemistry (eds. M. Florkin and E. H. Stotz) Elsevier,
Amsterdam 35:43-69 (see Fig. 4 of this paper).
11. In 1960 there was a meeting in Canberra Australia of many of the participants in the early debate
including myself. The conference book is "Haematin Enzymes" (eds. J. E. Falk, R. Lemberg and
R. K. Morton) Pergamon Press, Oxford (1961).
12. Mitchell, P. and Moyle, J. (1956) Disc. Faraday Soc. 21:258-265.
13. Mitchell, P. (1961) in: Biological Structure and Function Vol. 11. (eds T. W. Goodwin and O.
Lindberg) Academic Press, London 204-205.
14. Williams, R. J. P. (1956) Chem. Revs. 56:299-237.
15. Williams, R. J. P. (1956) Nature 177:304.
16. see Perutz, M. F. (1970) Nature 228:726-734.
17. Banerjee, R., Alpert, Y., Letterier, F. and Williams R. J. P. (1969) Biochemistry 8:2862-2868.
18. Hutchings, D. and Williams, R. J. P. (1956) Disc. Faraday Soc., 21: 192-197.
19. Williams, R. J. P. (1965) in: Non-Heine Iron Proteins: Role in Energy Conversion (ed. A. San
Pietro) Antioch Press, Ohio, 7-15.
20. Gao, Y., Boyd, J., Pielak, G. J. and Williams R. J. P. (1991) Biochemistry, 30:1928-1934 and
many papers on electron transfer proteins.
21 Williams R. J. P. (1975) in: Electron Transfer Chains and Oxidative Phosphorylation (eds. E,
Quagliariello, S. Papa, F. Palmieri, E. C. Slater and N. Siliprandi) North Holland Pub. Col.
Amsterdam 417-422.
22. Martin D. R. and Williams, R. J. P. (1976) Biochem. J. 153:181-189.
23. Pope, M. T. and Williams, R. J. P. (1959) J, (?hem. Soc. 3579-3583.
24 Joao, H. C., Taddei, N. and Williams, R. J. P. (1992) Eur. J. Biochem. 205:93-104, and many
other papers on phosphoglycerate kinase.
2:5. Boyer, P. D. (1993) Biochim. Biophys. Acta, 1140:215-250.
26. Williams R. J. P. (1970) in: Electron Transport and Energy Conservation (eds. J. M. Tager, S,
Papa, E. Quagliariello and E. C. Slater) Adriatica Edifice 7-23.
2"7. Williams, R. J. P. (1962) J. Theoret. Biol. 3:209-229.
28. Mitchell, P. (1961) in: Membrane Transport and Metabolism (eds. A. Kleinzeller and A. Kotyk)
Academic Press, New York pp. 22-34 and see Mitchell, P. and Moyle, J. (1958) Proc. Roy. Phys.
Soc. (Edinburgh) 27:61-72.
29. Stephen, B. P. (1960) D. Phil. Thesis, University of Edinburgh "The Biochemistry of Membranes
of Micro-organisms".
30. Mitchell, P. (1961) Biochem. s 81-24P.
3][. Mitchell, P. (1966) Chemiosmotic Coupling in Oxidative and Photosynthetic Phosphorylation.
Glynn Research Ltd., Bodmin U.K. and see Mitchell, P. (1966) Biol. Revs. 41:445-502.
32. Williams, R. J. P. (1972) Bioenergetics 3:81-91.
33. Williams, R. J. P. (1974) Annals, N.Y. Acad, Sci., 227:98-107.
34. The extract is from Electron Transport and Energy Conservation (eds. J. M. Tager, S. Papa, E.
Quagliariello and E. C. Slater.) Adriatica Edirice, Bari (1970) 379-381.
35. Mitchell, P. (1981) in: Evolving Life Sciences Vol. 1. Of Oxygen, Fuels and Living Matter (eds G.
Semenza) J. Wiley, Chichester, England, pp. 1-160; see Williams R. J. P. (1978) FEBS Letters,
85:9-19.
36. Williams, R. J. P. (1978) Trends in Biochem. Sci. 3:161-162.
I.
2.
3.
4.
5.
212
Williams
37. Williams, R. J. P. (1988) Ann. Rev. Biophys. Biophys. Chem. 17:71-97.
38. Gao, Y., McLendon, G., Pielak, G. J. and Williams, R. J. P. (1992) Eur. J. Biochem.
204: 337-352.
39. Joao, H. C. and Williams, R. J. P. (1993) Eur. J. Biochem. 216:1-18.
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