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Title: Oxygen-18 tracer studies of enzyme reactions with radical/cation diagnostic probes

Abstract

This review considers reactions of enzymes with the cyclopropanoid radical/cation diagnostic probes norcarane, 1,1-dimethylcyclopropane, and 1,1-diethylcyclopropane as elaborated by the use of {sup 18}O{sub 2} and {sup 18}OH{sub 2} to trace the origin of O-atoms incorporated during catalysis. The reactions of soluble and integral membrane diiron enzymes are summarized and compared to results obtained from cytochrome P450 studies. Norcarane proved to be an excellent substrate for the diiron enzyme toluene 4-monooxygenase and its engineered isoforms, with k {sub cat} and coupling between NADH utilization and total hydroxylated products comparable to that determined for toluene, the natural substrate. Results obtained with toluene 4-monooxygenase show that the un-rearranged and radical-rearranged alcohol products have a high percentage of O-atom incorporation (>80-95%) from O{sub 2}, while the cation-derived ring-expansion products have O-atom incorporation primarily derived from solvent water. Mechanistic possibilities accounting for this difference are discussed.

Authors:
 [1];  [2]
  1. Department of Biochemistry, University of Wisconsin, Madison, WI 53706 (United States)
  2. Department of Biochemistry, University of Wisconsin, Madison, WI 53706 (United States). E-mail: bgfox@biochem.wisc.edu
Publication Date:
OSTI Identifier:
20793194
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.2005.08.217; PII: S0006-291X(05)01943-1; 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; ALCOHOLS; CATALYSIS; CATIONS; ENZYMES; HYDROXYLATION; OXYGEN 18; RADICALS; SUBSTRATES; TOLUENE; TRACER TECHNIQUES; URANIUM NITRIDES

Citation Formats

Moe, Luke A., and Fox, Brian G. Oxygen-18 tracer studies of enzyme reactions with radical/cation diagnostic probes. United States: N. p., 2005. Web. doi:10.1016/J.BBRC.2005.0.
Moe, Luke A., & Fox, Brian G. Oxygen-18 tracer studies of enzyme reactions with radical/cation diagnostic probes. United States. doi:10.1016/J.BBRC.2005.0.
Moe, Luke A., and Fox, Brian G. Fri . "Oxygen-18 tracer studies of enzyme reactions with radical/cation diagnostic probes". United States. doi:10.1016/J.BBRC.2005.0.
@article{osti_20793194,
title = {Oxygen-18 tracer studies of enzyme reactions with radical/cation diagnostic probes},
author = {Moe, Luke A. and Fox, Brian G.},
abstractNote = {This review considers reactions of enzymes with the cyclopropanoid radical/cation diagnostic probes norcarane, 1,1-dimethylcyclopropane, and 1,1-diethylcyclopropane as elaborated by the use of {sup 18}O{sub 2} and {sup 18}OH{sub 2} to trace the origin of O-atoms incorporated during catalysis. The reactions of soluble and integral membrane diiron enzymes are summarized and compared to results obtained from cytochrome P450 studies. Norcarane proved to be an excellent substrate for the diiron enzyme toluene 4-monooxygenase and its engineered isoforms, with k {sub cat} and coupling between NADH utilization and total hydroxylated products comparable to that determined for toluene, the natural substrate. Results obtained with toluene 4-monooxygenase show that the un-rearranged and radical-rearranged alcohol products have a high percentage of O-atom incorporation (>80-95%) from O{sub 2}, while the cation-derived ring-expansion products have O-atom incorporation primarily derived from solvent water. Mechanistic possibilities accounting for this difference are discussed.},
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}
}