Electronic Theses and Dissertations

Date of Award

1-1-2011

Document Type

Dissertation

Degree Name

Ph.D. in Chemistry

Department

Chemistry and Biochemistry

First Advisor

Randy M Wadkins

Second Advisor

Gregory Tschumper

Third Advisor

Susan Pedigo

Relational Format

dissertation/thesis

Abstract

Carboxylesterases (CEs; EC 3.1.1.1) are ubiquitous enzymes responsible for the detoxification of xenobiotics. CEs hydrolyze carboxyl esters into their corresponding alcohol and carboxylic acid. Because of their biological functions, especially their roles in converting inactive prodrugs, such as the anti-cancer drug CPT-11, to their active metabolites, a good understanding of the mechanism of the hydrolysis reaction will give us a better direction for drug design. In this study, we used a multidisciplinary approach (computational simulation, molecular biology techniques and enzyme kinetic methods) to study the dynamic motions of CEs and the potential role of these motions in the catalytic mechanism of CEs. We used a Bacillus subtilis protein (pnbCE) as a model and demonstrated that the two loops in pnbCE, coil_5 and coil_21, were important in substrate conversion. Furthermore, we found that a C-C bond side chain rotation of Glu310 was a possible mechanism that the enzyme alternates between its active and inactive conformation. The results of these studies give us new insights about the structure-function relationship of CEs and therefore provide valuable information for approaches toward, for example, CE engineering for selected substrates or design of CE inhibitors.

Included in

Biochemistry Commons

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