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Title: Reactions of the diiron(IV) intermediate Q in soluble methane monooxygenase with fluoromethanes

Abstract

Soluble methane monooxygenases utilize a carboxylate-bridged diiron center and dioxygen to convert methane to methanol. A diiron(IV) oxo intermediate Q is the active species for this process. Alternative substrates and theoretical studies can help elucidate the mechanism. Experimental results for reactions with derivatized methanes were previously modeled by a combination of quantum mechanical/molecular mechanical techniques and the model was extended to predict the relative reactivity of fluoromethane. We therefore studied reactions of Q with CF {sub n}H{sub 4-n} (n = 1-3) to test the prediction. The kinetics of single-turnover reactions of Q with these substrates were monitored by double-mixing stopped-flow optical spectroscopy. For fluoro- and difluoromethane, conversion to the alcohols occurred with second-order rate constants less than that of methane, the values being 28,700 (CH{sub 4}) > 25,000 (CFH{sub 3}) > 9300 (CF{sub 2}H{sub 2}) M{sup -1} s{sup -1}. KIE values for C-H versus C-D activation above the classical limit were observed, requiring modification of the theoretical predictions.

Authors:
 [1];  [2]
  1. Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
  2. Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States). E-mail: lippard@mit.edu
Publication Date:
OSTI Identifier:
20793196
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemical and Biophysical Research Communications; Journal Volume: 338; Journal Issue: 1; Other Information: DOI: 10.1016/j.bbrc.2005.08.220; PII: S0006-291X(05)01946-7; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; CARBOXYLATION; HYDROXYLASES; KINETICS; METHANE; METHANOL; OXIDATION; QUANTUM MECHANICS; SUBSTRATES; SULFUR IONS

Citation Formats

Beauvais, Laurance G., and Lippard, Stephen J.. Reactions of the diiron(IV) intermediate Q in soluble methane monooxygenase with fluoromethanes. United States: N. p., 2005. Web. doi:10.1016/J.BBRC.2005.0.
Beauvais, Laurance G., & Lippard, Stephen J.. Reactions of the diiron(IV) intermediate Q in soluble methane monooxygenase with fluoromethanes. United States. doi:10.1016/J.BBRC.2005.0.
Beauvais, Laurance G., and Lippard, Stephen J.. Fri . "Reactions of the diiron(IV) intermediate Q in soluble methane monooxygenase with fluoromethanes". United States. doi:10.1016/J.BBRC.2005.0.
@article{osti_20793196,
title = {Reactions of the diiron(IV) intermediate Q in soluble methane monooxygenase with fluoromethanes},
author = {Beauvais, Laurance G. and Lippard, Stephen J.},
abstractNote = {Soluble methane monooxygenases utilize a carboxylate-bridged diiron center and dioxygen to convert methane to methanol. A diiron(IV) oxo intermediate Q is the active species for this process. Alternative substrates and theoretical studies can help elucidate the mechanism. Experimental results for reactions with derivatized methanes were previously modeled by a combination of quantum mechanical/molecular mechanical techniques and the model was extended to predict the relative reactivity of fluoromethane. We therefore studied reactions of Q with CF {sub n}H{sub 4-n} (n = 1-3) to test the prediction. The kinetics of single-turnover reactions of Q with these substrates were monitored by double-mixing stopped-flow optical spectroscopy. For fluoro- and difluoromethane, conversion to the alcohols occurred with second-order rate constants less than that of methane, the values being 28,700 (CH{sub 4}) > 25,000 (CFH{sub 3}) > 9300 (CF{sub 2}H{sub 2}) M{sup -1} s{sup -1}. KIE values for C-H versus C-D activation above the classical limit were observed, requiring modification of the theoretical predictions.},
doi = {10.1016/J.BBRC.2005.0},
journal = {Biochemical and Biophysical Research Communications},
number = 1,
volume = 338,
place = {United States},
year = {Fri Dec 09 00:00:00 EST 2005},
month = {Fri Dec 09 00:00:00 EST 2005}
}