Document Detail

Mechanism and stereochemical course at phosphorus of the reaction catalyzed by a bacterial phosphotriesterase.
MedLine Citation:
PMID:  2835095     Owner:  NLM     Status:  MEDLINE    
The reaction mechanism for the phosphotriesterase from Pseudomonas diminuta has been examined. When paraoxon (diethyl 4-nitrophenyl phosphate) is hydrolyzed by this enzyme in oxygen-18-labeled water, the oxygen-18 label is found exclusively in the diethyl phosphate product. The absolute configurations for the (+) and (-) enantiomers of O-ethyl phenylphosphonothioic acid have been determined by X-ray diffraction structural determination of the individual crystalline 1-phenylethylamine salts. The (+) enantiomer of the free acid corresponds to the RP configuration. The RP enantiomer of O-ethyl phenylphosphonothioic acid has been converted to the SP enantiomer of EPN [O-ethyl O-(4-nitrophenyl) phenylphosphonothioate]. (SP)-EPN is hydrolyzed by the phosphotriesterase to the SP enantiomer of O-ethyl phenylphosphonothioic acid. The enzymatic reaction therefore proceeds with inversion of configuration. These results have been interpreted as an indication of a single in-line displacement by an activated water molecule directly at the phosphorus center of the phosphotriester substrate. (RP)-EPN is not hydrolyzed by the enzyme at an appreciable rate.
V E Lewis; W J Donarski; J R Wild; F M Raushel
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Biochemistry     Volume:  27     ISSN:  0006-2960     ISO Abbreviation:  Biochemistry     Publication Date:  1988 Mar 
Date Detail:
Created Date:  1988-06-14     Completed Date:  1988-06-14     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1591-7     Citation Subset:  IM    
Department of Chemistry, Texas A&M University, College Station 77843.
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MeSH Terms
Chemical Phenomena
Organothiophosphorus Compounds / metabolism*
Phosphoric Monoester Hydrolases / metabolism*
Pseudomonas / enzymology*
Grant Support
Reg. No./Substance:
0/Organothiophosphorus Compounds; EC 3.1.3.-/Phosphoric Monoester Hydrolases

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