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James K. Coward, Ph.D. is Professor of Medicinal Chemistry
and Professor of Chemistry, University of Michigan. He obtained
the A.B. degree with a major in chemistry from Middlebury
College in 1960, after which he was employed as a chemist
by American Cyanamid Co. in Stamford, CT. He returned to school
at Duke University, intending to pursue a Ph.D. in physical
organic chemistry. Following a stimulating introduction to
biochemistry by Prof. Philip Handler, he moved to the State
University of New York at Buffalo to study medicinal chemistry
with Prof. B. R. Baker (Ph.D., 1967). Postdoctoral research
in bioorganic chemistry with Prof. Thomas C. Bruice at the
University of California, Santa Barbara, supported by a NIH
fellowship, completed his formal education at an exciting
time when the fields of medicinal chemistry and mechanistic
enzymology could interact in a synergistic manner.
In 1969, Coward joined the faculty of the Department of
Pharmacology at Yale University School of Medicine. In 1979,
he moved to the Department of Chemistry, Rensselaer Polytechnic
Institute and in 1987, accepted his present position at the
University of Michigan. Initial research involved mechanistic
studies of catechol O-methyltransferase and related model
reactions. This research was expanded to include the related
alkyl transfer reactions catalyzed by spermidine synthase
and spermine synthase, two key steps in polyamine biosynthesis.
In addition to steady-state kinetic studies, this research
involved the use of chiral methyl and methylene substrates
to determine the stereochemistry of enzyme-catalyzed alkyl
transfer reactions. First-generation inhibitor synthesis focused
on metabolically stable analogs of the products, S-adenosylhomocysteine
and methylthioadenosine. Second-generation inhibitor synthesis
was aimed at “multisubstrate adduct” inhibitors
of catechol O-methyltransferase, spermidine synthase (AdoDATO,
AdoSpd), and spermine synthase (AdoDATAD). In related research,
a series of α-methyl polyamines, designed to resist oxidative
metabolism, proved to be useful for the study of polyamine
function in vivo.
The biosynthesis and hydrolysis of poly-γ-glutamate
derivatives of reduced folates and antifolates are catalyzed
by folylpoly-γ-glutamate synthetase, an ATP-dependent
ligase, and γ-glutamyl hydrolase, a cysteine peptidase, respectively.
Mechanistic research on the synthetase included demonstration
of a transient acyl phosphate intermediate using 17O-
and 18O-labeled substrates, and kinetic studies
on multiple ligations using substrate trapping and pulse-chase
methods. Development of a new fluorescence assay for the hydrolase
led to an extensive kinetics analysis of enzyme-catalyzed
isopeptide hydrolysis. Based on these mechanistic studies,
the design and synthesis of a series of phosphinic acid-containing
pseudopeptides resulted in potent and specific inhibitors
of the synthetase, and methods for the synthesis of internal
epoxide peptidomimetics as potential inhibitors of the hydrolase
were developed. Extension of this approach has resulted in
the synthesis of aryl phosphinic acids as potential inhibitors
of dihydrofolate synthetase, a new target for antimalarial
drug design, and alkyl phosphinic acids as potent inhibitors
of glutathionylspermidine synthetase, a new target for antitrypanosomal
drug design.
In the area of carbohydrate chemistry, the Coward group has
investigated several glycosyltransferases, including oligosaccharyltransferase.
Use of isotopically labeled peptides and disaccharides, as
well as developing an epoxide fluoridolysis method for the
synthesis of 5-fluoro 2-amino sugars have provided mechanistic
insight and inhibitors for this important group of enzymes.
Coward has served the medicinal chemistry community in a variety
of leadership positions. He was a member of the Long Range
Planning Committee, ACS Division of Medicinal Chemistry (1989-1991)
and Alternate Councilor and member of the Executive Committee,
ACS Division of Biological Chemistry as (1991-1993). He has
served on the Editorial Boards of Biochemical Pharmacology
(1984-1996), Journal of Medicinal Chemistry (1988-1992) and
Annual Review of Pharmacology & Toxicology (1997-2002).
At the University of Michigan, he was the Program Director
of the Chemistry-Biology Interface Training Program (1995-2005)
and Principal Investigator of the underlying NIH Training
Grant. He was the first Chair of a newly created Department
of Medicinal Chemistry at the University of Michigan (1998-2004)
and Director of the longstanding Interdepartmental Program
in Medicinal Chemistry Program during that period. As a member
of NIH study sections (Medicinal Chemistry ‘A’,
1979; Experimental Therapeutics, 1979-1982) and review committees
(Pharmacological Sciences Review Committee (1987-1991), and
numerous advisory panels (NIH, NSF), he has been an advocate
for academic medicinal chemistry research. He has been mentor
for over 50 graduate students and postdoctoral associates,
as well as over 25 undergraduate students. He is a Fellow,
Chemistry Section, American Association for the Advancement
of Science (2002).
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