The discovery of a method by which
crystalline sugar can be synthesized
enzymatically is significant for its scientific implications. Since the functioning
of a living cell depends on the sum total
of a great multitude of enzymatic resynthesized
studies in the
actions taking place within it, the understanding of the procrsses involved is of
metabolism
plants and animals
primary importance.
The knowledge of how sucrose is
W. Z. Hassid formed may lead to an understanding of
conditions whereby greater yields of
Carbohydrates, essential foods in hu- two or more different monosaccharides. sugar can be obtained from sugar beets
man nutrition, are many factured by green The starch molecules in turn combine to and sugar cane. Since it is known that
plants. All other living creatures are com- form starch granules and the cellulose inorganic phosphate is involved in the
pletely dependent upon plants, because niolecules form cellulose fibers. The poly- mechanism of sucrose formation, higher
they- alone have the power to make sugars saccharides-cellulose, hemi-cellulose, and sugar yields may be concerned in part
from the simple materials of carbon di- others-provide the plant with a struc- with phosphate fertilization, although
oxide arid water. This is accomplished by tural frame, giving the plant rigidity. many other factors are undoubtedly ina process called photosyuthesis.
Cellulose, xylan, and hemi-cellulose usu- volved.
As a result of photosynthesis, gaseous ally make up the bulk of the plant.
The same enxqme which forms sucrose
carbon dioxide combines with hydrogen
from glucose-phosphate and fructose also
from water in the presence of light and
will combine sucrose with a number of
the green pigment-chlorophyll-in
the Sugar Formation
simple sugars other than fructose, formOne phase of the work o f the Uivi- ing new disaccharides. Four new crystalliving cell to form sugar arid oxygen. Thus
far scientists have not been able to imitate sion of Plant Nutrition is the study of line sugars were synthesiLed in the
how complex sugars are formed-synthethis process i n the laboratory.
laboratory hy the aid of this enzyme.
The sugars manufactured by plants sized-from simpler building units, and
It is generally accepted that enLymes
serve as potential stores of energy. In also how these complex sugars, after are specific in their action with regard
living cells they combine with oxygen and being formed, are broken down-deto substrates-a certain etuyme will perare oxidized, liberating energy that corre- graded-through a reverse process. For lorm only one specific reaction. For exsponds to the energy from the combustion example, by what mechanism do glucose ample. the enzyme amylase or diastase
of heating materials in factories. In the and fructose condense LO form sucrose, is capable of breaking down only starch
process of oxidation about 100 kilocalor- which accumulates in large quantities in to maltose and dextrins. Another enzyme,
ies of heat are released for each 10 grams many plants; or how is glucose con- invertase, will split sucrose to glucose
of carbon they contain.
densed to form the giant starch or cellu- and fructose, but will not attack any
The energy liberated in the respira- lose molecule.
other complex sugar. In the case of sution-oxidation-process
is used for praccrose phosphorylase, apparently there is
tically all the metabolic processes of the
an enzyme whirh is characterized by its
plant. Respiration provides the energy Enzymes
versatility. It is capable of synthesizing
Synthesis as well as degradation of or- several disaccharides from various monorequired by the plant for the synthesis
o f numerous organic compounds, such as ganic compounds in nature is carried out saccharides and also of reversing the
by the aid of enzymes. The enzymes are reaction-breaking the romplex sugars
proteins, fats, vitamins, etc.
large complex protein molecules which down to their constituent monosaccharare present in all living cells, One of the ides.
Complex Carbohydrates
best-known examples of an enzyme is
From these studies much has been
Glucose-corn sugar or dextrose, and invertase which breaks down sucrose to learned about the mechanism of the
frwtose-fruit sugar or levulose, are the glucose and fructose. Enzymes are re- reactions involved i n the synthesis of
so-called monosaccharides, or simple sponsible for the fermentation of sugar disaccharides. It was found that the ensugars, which are readily formed in the to carbon dioxide and alcohol.
zyme-sucrose phosphorylase-is capable
In connection with the study of the of synthesizing sucrose and other diprocess of photosynthesis, and serve as
building units or blocks for the forma- process of sucrose formation, a search is saccharides without phosphate taking
tion of the more complex carbohydrates. being made to find an enzyme which place in the reartion. The phosphate in
The disaccharide sucrose which is ordi- could combine glucose and fructose to glucose-phosphate can be substituted by
nary sugar consists of a molecule of the form the disaccharide, sucrose.
other monosaccharides.
Several years ago a research worker
monosaccharide, glucose and the monoIt is possible that many of the plant
saccharide, fructose, formed through the in the Department of Bacteriology suc- carbohydrates, such as inulin or pectins,
elimination of a molucule of water, which ceeded in making an enzyme prepara- are synthesized by a similar mechanism.
leaves the two monosaccharides being tion from the bacterium Pseudomonas which does not require phosphate.
held by an oxygen bridge. Another di- saccharophila which could break down
saccharide, maltose, is similarly formed sucrose in the presence of inorganic
from two glucose units joined by an phosphate, forming glucose-phosphate Radioactive Sugars
Radioactive glucosc. ! I iicto3e, sucrose,
oxygen atom. In its molecule, raffinose and fructose. It was found later that
and starch can be prepaIt4 b j exposing
contains glucose, fructose, and galactose. this process could be reversed-glucosePolysaccharides such as starch, glycogen, phosphate could be combined with fruc- various plants to radioactive carbon dior cellulose, consist of many hundreds of tose to form sucrose, splitting off oxide in the presence of light and allowinorganic phosphate in the reaction. ing them to photosynthesize f o r certain
glucose units.
The complex sugars as well as the poly- Thus by means of an enzyme elaborated periods of time. The radioactive ( ai 110saccharides may be built of the same by bacteria, sugar w a s synthesized in the hydrates may then be isolated and sepamonosaccharide unit, or in some cases, of laboratory for the first time.
Continued on page 14
Radioactive Sugars
for
of
CALIFORNIA A G R I C U L T U R E , D E C E M B E R , 1948
11
SUGARS
Continued from page 11
rated. They are now being used in the
study of the mechanism of carbohydrate
formation and breakdown in plants.
Radioactive glucose prepared in the
laboratory is being used in the Medical
School to study the problem of the utilization of glucose by diabetic animals. The
problem of how a diabetic animal oxidizes sugar is still obscure.
,
1 he discovery of the enzymatic s j n thesis of sucrose from glucose-phosphate
and fructose permits the study of the
metabolism of this disaccharide in plants
and animals with regard to each monosaccharide constituent. Thus far the behavior of glucose or fructose during the
course of metabolism could not he ohserved since it has been impossible by
ordinary methods to distinguish one
sugar fragment from the other in their
final utilization by plants and animals.
The use of the tracer technique,
whereby radioactive carhon isotopes are
incorporated into the molecules, permits
a direct observation o f the course of
metabolism of individual compounds.
As sucrose now can be synthesized enzymatically from glucose-phosphate and
fructose, i t is possihle to label each half
of the molecule of sucrose at will. Radioactive sucrose with a labeled or tagged
glucose molecule can be prepared by
combining radioactive glucose-phosphate
with inactive fructose by the aid of the
bacterial enzyme. Sucrose with a tagged
fructose molecule then can be synthetically made from inactive glucose-phosphate and radioactive fructose and the
same ehzyme.
These t w o radioactivc sugars actually
have been synthesized in the laboratory,
and it is hoped to learn about the fate of
each half of the sucrose molecule, by following their course of metabolism in
plants and animals.
’*
~-
W . Z. Hassid is Professor oj Plant Nutrition
and Chemist in the Experiment Station, Berkeley.
The above progress report is based upon Research Projert No. 1.369.
is far from true. While much is known
about the pathology of the disease, and
something about the virus, little is known
about the development of the disease in
different species of birds, the immune reactions, and the basic source of the infection-that is, where it over-winters. In
exploring these fields, improved means of
control or possible eradication may be
found. Poultrymen should recognize the
need for continuing such basic research.
The cautious, intelligent use of live-virus
PE vaccine does provide an expedient
method for reducing the economic losses
due to this infection where it exists and
is a problem. Such use gives time for
needed investigations.
Other Control Measures
A copy of the publications listexhere may be
obtained without charge from the local ojjice of
the Farm Advisor or by addressing a request to
Publications Ojjice, College of Agriculture, University of California, Berkeley 4, California.
S W I N E FEEDING E X P E R I M E N T S , b y
E . H . Hughes and Hubert Heitman, Jr.
Bul. 7 0 9 , O c t o b e r , 1 9 4 8 .
The daily g a i n i n w e i g h t of p i g s is imp o r t a n t t o t h e s w i n e raiser. T h i s bulletin
r e p o r t s t h e results of f o u r investigations,
which s h o w that ( 1 ) c o o k e d lima beans
rnay efliciently be added t o the d i e t of
pigs, saving some tankage; ( 2 ) potato
meal can replace p a r t of t h e barley in the
ration ; ( 3 ) s o y b e a n meal is a n excellent
plant p r o t e i n ; arid ( 4 ) a g o o d , costteducirtg practice is t o allow hogs t o harvest a c r o p of dwarf rnilo a n d c o w p e a s .
Poultrymen would be unwise to consider that live-virus vaccination is the
only method to control PE. There are
other possibilities. First, use the excellent
diagnostic facilities available. promptly SPRINKLING FOR IRRIGATION, b y
and adequately.
F . J . Veihnaeyer. C i r . 588, N o v e n i b e r .
Second, sources of new infection should 1948.
be eliminated: adult or started birds
S p r i n k l i n g f o r irrigation has a place
should not be brought to the ranch.
in California agriculture, b u t i t is n o t a
Third, sound sanitation-curtailed vis- cure-all. T h i s circular c o v e r s f o u r m a i n
its, free areas for loading and unloading, q u e s t i o n s : The k i n d of t o p o g r a p h y , soil,
etc.-should
be practiced. Continuous climate, a n d c r o p s which make the use of
brooding should be avoided.
sprinklers a d v i s a b l e . T h e k i n d of s y s t e m
Fourth, formalin-killed vaccines might [he f a r m m a y treed. The cost a n d the jusbe useful.
tification f o r t h e costs.
Lastly, and only until better means are
available, in those areas where pneu- INVESTIGATIONS OF T H E FLOR
inoencephalitis is known to exist or is an SHERRY P R O C E S S , b y W . V . Cruess.
immediate threat, live-virus vaccines may Bul. 710, O c t o b e r , 1948.
be helpful.
Though it may be assumed that live- or a natural outbreak. The effect of livevirus PE vaccine provides an easy-to-use virus vaccine on the future of the birds is
method of conferring solid immunity to not known. The product is subject to misvaccinated birds and probably provides use, and there is no visible take. The staa short time, passive immunity to chicks bility of the vaccine virulence is not fully
hatched from vaccinated hens, there are established. Most important, live-virus
numerous limitations. However, it is not vaccine perpetuates the disease or may
safe or a good immunizing agent for introduce the infection into clean areas.
chicks under four weeks of age; it should
A. S. Rosenwald is Specialist in Poultry Panot be used on laying birds, and birds to
be vaccinated should be in good health. thology, AgricuItural Extension Service, Berkeley.
Since the vaccine infection spreads, all
Published evidence and papers prescnted at
other birds on the ranch should be im- various meetings have been drawn on freely in
mune as a result of previous vaccination preparing this report.
VACCINE
DONATIONS FOR AGRICULTURAL RESEARCH
Continued froni page 6
cine because there i s no readable take
such as poultrymen check following
laryngotracheitis or fowl pox vaccination.
Like any living product, live-virus vaccines are subject to deterioration. Because
there is no easily readable take, it is difficult to tell whether such loss of effectiveness has or has not occurred.
Poultrymen have been lulled into a
false sense of security, thinking that livevirus vaccines provide the final answers to
the control o f pneumoencephalitis. This
14
Gifts to the University of California for research by the College of Agriculture
accepted in October, 1948
BERKELEY
Dr. Gabriele Goidanich and Dr. C. M. Tompkins.
I
. . . . . . . . A rare early
Italian treatise on diseases of
cereal grains, 1759
Lederle Laboratories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 irams soecial feed sumlement
National Research Council. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . :. . . . . . . . . . .$500.00
For work in plant microbiology
Sugar Research Foundation, Inc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .S1,000.00
For food technology research
5702.00
Sugar Research Foundation, Inc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
For plant nutrition research
r.
__
RIVERSIDE
California Fertilizer Association . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S2.000.00
For studies on determination of effects of various nutrient variables on absorption of
phosphorus by citrus plants
C A L I F O R N IA AG R I C U LT U RE, DE C EM BE R , 1948