Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Ross, Matt

Committee Member

Crow, Allen

Committee Member

Chambers, Jan

Committee Member

Filipov, Nikolay

Date of Degree

8-11-2007

Document Type

Graduate Thesis - Open Access

Major

Veterinary Medical Science

Degree Name

Master of Science

College

College of Veterinary Medicine

Department

Department of Basic Sciences

Abstract

Carboxylesterases (CEs) metabolize a wide range of endogenous compounds and xenobiotics containing ester bonds. Crystal structures of mammalian CEs indicate a ?side door? located adjacent to the catalytic gorge that may act as an alternative pore for the trafficking of substrates and products. This study investigated the role of the ?gate? residue of the side door during para-Nitrobenzyl esterase (pnb CE)-catalyzed hydrolysis of esters. Purified recombinant pnb CE proteins were examined for their hydrolytic activity toward several esters. Mutation of the gate residue altered the kinetic parameters of pnb CE toward these substrates, demonstrated by increased Km values and decreased Vmax values. Site-specific mutations of the ?gate? residue also affected the sensitivity of the enzyme toward inhibiting organophosphate compounds. A distinct possibility is that the side door mutants affect substrate hydrolysis by increasing the steric hindrance and/or electrostatic repulsion between the substrate and the active site catalytic residues.

URI

https://hdl.handle.net/11668/15338

Comments

Carboxylesterase||metabolism||pyrethroids

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