DEPARTMENT OF CHEMISTRY AND BIOCHEMISTRY
SPRING 2016 DEPARTMENTAL SEMINARS::
John H. Dawson
“Caught in the Act: Monitoring O-O Bond Cleavage to Form
Cytochrome P450 Compound I in Real Time”
Abstract
Cytochrome P450 is a remarkable hemecontaining oxygenase that activates O2
for O-atom insertion into unactivated
hydrocarbons.
The active catalyst is a
ferryl [oxo-iron(IV)] porphyrin radical
(Compound I) that can also be made from
the ferric enzyme by reaction with peracids
and other O-atom donors. Using rapid-scan
stopped-flow techniques, we have observed
an acylperoxo-ferric heme intermediate that
undergoes O-O bond cleavage to generate
Compound I. Thus we can directly follow
Compound I formation in real time and investigate factors
that influence its formation rate, providing useful information
regarding the mechanism of dioxygen activation by P450.
Although Compound I is the most powerful P450 intermediate,
preceding peroxo and hydroperoxo intermediates have been
proposed as secondary oxidants. Using a P450 variant that
doesn’t form Compound I, we have investigated the role of
these two species as second active P450 oxidants. Funding:
NIH GM 26730; NSF MCB 0820456
Daniel L. Reger
“Dinuclear Metallacycles with Single Anion Bridges and
Supramolecular MOFs Organized by Flexible and Robust
π - π Stacking Interactions.”
Abstract
A series of dinuclear metallacycles
supported ditopic bis(pyrazolyl)methane
ligands (Lm) of the type [M2(μ-X)(μ-Lm)2]
(ClO4)3 (M = Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+,
Cd2+) (X = CN-, F-, Cl-, OH-, Br-) have been
prepared. These complexes represent
the first extensive series of dinuclear
complexes with a linear or nearly linear
M(II)–X–M(II) bridging arrangement. They
show strong antiferromagnetic magnetic
properties and provide a unique opportunity to determine
the impact of systematic chemical and structural changes on
these properties, both in the solid state and solution.
We have prepared a series of supramolecular MOF complexes
by using ligands that couple a carboxylate donor with the
1,8-naphthalimide group, a supramolecular tecton that forms
unusually robust and flexible π-π stacking interactions. Many
of these solids have unusual properties, most notably singlecrystal to single-crystal gas/solid transformations.
The University of South Carolina is an equal opportunity institution.
FRIDAY
May 6, 2016
3:00 p.m.
Jones Physical
Science Center
(JONES) 006