Biochemistry Department

Hille Research Group

Welcome to the Hille Research Group


            My research program focuses the reaction mechanisms of oxidoreductase enzymes - particularly those possessing molybdenum or flavin in their active sites - and biological electron transfer. The molybdenum-containing enzymes catalyze the incorporation of oxygen into a variety of organic and inorganic compounds, and constitute an important class of oxidoreductase enzymess. These enzymes are only poorly understood in comparison to other biological systems that contain heme, flavin, non-heme iron or copper. Working with representative members of each of the three major families of molybdenum enzymes, we have successfully identified for each the fundamental aspects of the catalytic sequences of these enzymes. Particularly in the case of the molybdenum hydroxylase family (as represented by xanthine oxidase), work in our laboratory has elucidated the chemical course of the reaction as well as the role of specific active site residues in accelerating reaction rate. Our present work in this area involves kinetic, spectroscopic and crystallographic studies in conjunction with mutagenic work to gain further insight into the basic elements of catalysis at play in these enzymes, as well as modeling of the reaction intermediates and transition states using computational approaches.

            Several of the enzymes we are investigating possess multiple redox-active centers within a single polypeptide, and are useful systems in which to examine the factors governing rates of biological electron transfer without the complication of protein-protein interactions. We utilize pH-jump stopped-flow, flash photolysis and pulse radiolysis methodologies to examine the rates of electron transfer within several such enzymes possessing two to as many as nine redox-active centers. Our present studies are focused on elucidating specific pathways of electron transfer within these systems, particularly with regard to understanding the role of branches in these pathways and the function of centrally located sites that possess "outlier" reduction potentials – either very high or very low – in these electron transfer systems.

research for hille

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General Campus Information

University of California, Riverside
900 University Ave.
Riverside, CA 92521
Tel: (951) 827-1012

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Department Information

Department of Biochemistry
1463 Boyce Hall

Department Chair's Tel: (951) 827-3598
Fax: (951) 827-2364
Email: Biochem@ucr.edu

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