Professor Rajendra Rathore

 

Richard C. Holz, Ph.D.
Professor, Dean-Helen Way Klingler College of Arts & Sciences
Phone: (414) 288-7230
E-mail: richard.holz@marquette.edu

Biography

Professor Holz earned his bachelor’s degree at Bemidji State University, his master’s degree at the University of Minnesota-Duluth and his doctorate in chemistry from The Pennsylvania State University.  He was a National Institutes of Health Postdoctoral Research Fellow at the University of Minnesota after which he joined the faculty at Utah State University before moving to Loyola University Chicago as the Chair of the Chemistry Department, before moving to Marquette.  He has contributed to more than 90 research articles and co-invented two patents.

Research Interests

The Holz research group interfaces the general areas of inorganic chemistry, mechanistic enzymology and biophysical chemistry.  In general the Holz group is interested in structure/function studies of metalloenzymes some of which are antimicrobial targets.  Within these studies, the Holz group uses a wide variety of biochemical and biophysical methods such as enzyme kinetics, site-directed mutagenesis, isothermal titration calorimetry, UV-Vis, NMR and EPR spectroscopies.  Current projects in the Holz group center on an NSF sponsored project to study the catalytic mechanism of nitrile hydratases (NHases) and an NIH sponsored project to study the zinc dependent dapE-encoded desuccinylase from Haemophilus influenzae (DapE).

NHases are metalloenzymes in the nitrile degradation pathway that catalyze the hydration of nitriles to their corresponding amides at ambient pressures and temperatures at physiological pH.  NHases have attracted substantial interest as biocatalysts in preparative organic chemistry and are used in many applications such as the large scale industrial production of acrylamide and nicotinamide.  Because of their exquisite reaction specificity, the nitrile-hydrolyzing potential of NHase enzymes is becoming increasingly recognized as a truly new type of “Green” chemistry.  However, little is understood about how NHase enzymes function.  Therefore, a better understanding of the structure and reaction mechanism of NHase enzymes will enable access to nitrile-hydrolyzing materials with broader substrate ranges, higher activities, and greater stabilities. 

DapE is a member of the lysine biosynthetic pathway, which also produces meso-diaminopimelic acid (meso-DAP), an essential component of bacterial cell wall synthesis.  Disruption of the biosynthesis of meso-DAP has been shown to result in cell death for several bacteria.  Since drug resistance in pathogenic bacteria has increased tremendously in the past few years, DapE’s are potential novel pharmaceutical targets for which a human counterpart does not exist.  Therefore, the design and synthesis of small molecules that inhibit DapE may lead to a new class of antibiotics. 

Recent Publications:

Current Funding

National Science Foundation- (CHE-1058357)7/1/2011 to 6/30/2014, “Collaborative Research on the Catalytic Mechanism of Nitrile Hydration Catalysts”  The goals of this proposal are to elucidate the mechanism of nitrile hydration by NHase and to ascertain the generality of the mechanism by comparison of three distinct NHases.  These studies will inform the design of reaction conditions for the use of NHase as an industrial biocatalyst for organic chemical processing, industrial synthesis, and bioremediation.  In addition, successful completion of the work will inform the design of synthetic nitrile hydrating catalysts with tailored catalytic properties.  An interdisciplinary approach will be used that incorporates kinetic, spectroscopic, biochemical, and X-ray crystallographic methods

National Institutes of Health – (R15 AI085559-01A1) 5/1/2010 to 4/30/2014, "A New Antibacterial Drug Target: Analyzing Inhibitor Binding to a Bacterial Metallohydrolase” the hypothesis of this proposal is that highly potent inhibitors of enzymes in the mDAP/lysine biosynthetic pathway will provide a previously undescribed class of antibacterials.  It has been shown that deletion of the gene encoding for DapE is lethal to Helicobacter pylori and Mycobacterium smegmatis indicating that DapE's are essential for cell growth and proliferation.  Therefore, the goal of this proposal is to discover new antimicrobial lead compounds for DapE enzymes and analyze the determinants of substrate/inhibitor binding.


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