Ely, Fernanda and Hadler, Kieran S. and Gahan, Lawrence R. and Guddat, Luke W. and Ollis, David L. and Schenk, Gerhard (2010) The organophosphate-degrading enzyme from Agrobacterium radiobacter displays mechanistic flexibility for catalysis. Biochemical Journal, 432 (3). pp. 565-573. ISSN 0264-6021
Download (538kB)
|
Abstract
The OP (organophosphate)-degrading enzyme from Agrobacterium radiobacter (OpdA) is a binuclear metallohydrolase able to degrade highly toxic OP pesticides and nerve agents into less or non-toxic compounds. In the present study, the effect of metal ion substitutions and site-directed mutations on the catalytic properties of OpdA are investigated. The study shows the importance of both the metal ion composition and a hydrogenbond network that connects the metal ion centre with the substrate-binding pocket using residues Arg254 and Tyr257 in the mechanism and substrate specificity of this enzyme. For theCo(II) derivative of OpdA two protonation equilibria (pKa1 ∼5; pKa2 ∼10) have been identified as relevant for catalysis, and a terminal hydroxide acts as the likely hydrolysis-initiating nucleophile. In contrast, the Zn(II) and Cd(II) derivatives only have one relevant protonation equilibrium (pKa ∼4–5), and theμOHis the proposed nucleophile. The observed mechanistic flexibility may reconcile contrasting reaction models that have been published previously and may be beneficial for the rapid adaptation of OP-degrading enzymes to changing environmental pressures.
Item Type: | Article |
---|---|
Additional Information: | The final version of record is available at http://www.biochemj.org DOI: doi:10.1042/BJ20101054 . |
Keywords: | Agrobacterium radiobacter; crystal structure; hydrogen bonding; OpdA; organophosphate-degrading enzyme; organophosphate pesticide; site-directed mutagenesis; |
Academic Unit: | Faculty of Science and Engineering > Chemistry |
Item ID: | 3677 |
Depositing User: | Gary Schenk |
Date Deposited: | 23 May 2012 15:31 |
Journal or Publication Title: | Biochemical Journal |
Publisher: | Portland Press |
Refereed: | Yes |
URI: | |
Use Licence: | This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here |
Repository Staff Only(login required)
Item control page |
Downloads
Downloads per month over past year