Epoxide hydrolase-catalyzed enantioselective conversion of trans-stilbene oxide: Insights into the reaction mechanism from steady-state and pre-steady-state enzyme kinetics
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388971%3A_____%2F16%3A00460095" target="_blank" >RIV/61388971:_____/16:00460095 - isvavai.cz</a>
Result on the web
<a href="http://dx.doi.org/10.1016/j.abb.2015.12.008" target="_blank" >http://dx.doi.org/10.1016/j.abb.2015.12.008</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1016/j.abb.2015.12.008" target="_blank" >10.1016/j.abb.2015.12.008</a>
Alternative languages
Result language
angličtina
Original language name
Epoxide hydrolase-catalyzed enantioselective conversion of trans-stilbene oxide: Insights into the reaction mechanism from steady-state and pre-steady-state enzyme kinetics
Original language description
A detailed kinetic study based on steady-state and pre-steady-state measurements is described for the highly enantioselective epoxide hydrolase Kau2. The enzyme, which is a member of the alpha/beta-hydrolase fold family, preferentially reacts with the (S,S)-enantiomer of trans-stilbene oxide (TSO) with an E value of similar to 200. The enzyme follows a classical two-step catalytic mechanism with formation of an alkyl-enzyme intermediate in the first step and hydrolysis of this intermediate in a rate-limiting second step. Tryptophan fluorescence quenching during TSO conversion appears to correlate with alkylation of the enzyme. The steady-state data are consistent with (S,S) and (R,R)-TSO being two competing substrates with marked differences in k(cat) and K-M values. The high enantiopreference of the epoxide hydrolase is best explained by pronounced differences in the second-order alkylation rate constant (k(2)/K-S) and the alkyl-enzyme hydrolysis rate k(3) between the (S,S) and (R,R)-enantiomers of TSO. Our data suggest that during conversion of (S,S)-TSO the two active site tyrosines, Tyr(157) and Tyr(259), serve mainly as electrophilic catalysts in the alkylation half-reaction, polarizing the oxirane oxygen of the bound epoxide through hydrogen bond formation, however, without fully donating their hydrogens to the forming alkyl-enzyme intermediate. (c) 2015 Elsevier Inc. All rights reserved.
Czech name
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Czech description
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Classification
Type
J<sub>x</sub> - Unclassified - Peer-reviewed scientific article (Jimp, Jsc and Jost)
CEP classification
CE - Biochemistry
OECD FORD branch
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Result continuities
Project
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Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2016
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Archives of Biochemistry and Biophysics
ISSN
0003-9861
e-ISSN
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Volume of the periodical
591
Issue of the periodical within the volume
FEB 2016
Country of publishing house
US - UNITED STATES
Number of pages
10
Pages from-to
66-75
UT code for WoS article
000370394400008
EID of the result in the Scopus database
2-s2.0-84952361266