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Title: Crystallographic and Catalytic Studies of the Peroxide-Shunt Reaction in a Diiron Hydroxylase

Abstract

A diiron hydroxylase reaction typically begins by combination of O{sub 2} with a diferrous center to form reactive intermediates capable of hydrocarbon hydroxylation. In this natural cycle, reducing equivalents are provided by specific interactions with electron transfer proteins. The biological process can be bypassed by combining H{sub 2}O{sub 2} with a diferric center, i.e., peroxide-shunt catalysis. Here we show that toluene 4-monooxygenase has a peroxide-shunt reaction that is {approx}600-fold slower than catalysis driven by biological electron transfer. However, the toluene 4-monooxygenase hydroxylase-effector protein complex was stable in the presence of 300 mM H{sub 2}O{sub 2}, suggesting overall benign effects of the exogenous oxidant on active site structure and function. The X-ray structure of the toluene 4-monooxygenase hydroxylase-effector protein complex determined from crystals soaked in H{sub 2}O{sub 2} revealed a bound diatomic molecule, assigned to a cis-{mu}-1,2-peroxo bridge. This peroxo species resides in an active site position adjacent to the hydrogen-bonding substructure established by effector protein binding and faces into the distal cavity where substrate must bind during regiospecific aromatic ring hydroxylation catalysis. These results provide a new structural benchmark for how activated intermediates may be formed and dispatched during diiron hydroxylase catalysis.

Authors:
;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1005929
Resource Type:
Journal Article
Journal Name:
Biochemistry-US
Additional Journal Information:
Journal Volume: 48; Journal Issue: (38) ; 09, 2009; Journal ID: ISSN 0006-2960
Country of Publication:
United States
Language:
ENGLISH
Subject:
59 BASIC BIOLOGICAL SCIENCES; 99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; AROMATICS; BENCHMARKS; CATALYSIS; ELECTRON TRANSFER; HYDROCARBONS; HYDROXYLASES; HYDROXYLATION; OXIDIZERS; PROTEINS; SUBSTRATES; TOLUENE

Citation Formats

Bailey, Lucas J, Fox, Brian G, and UW). Crystallographic and Catalytic Studies of the Peroxide-Shunt Reaction in a Diiron Hydroxylase. United States: N. p., 2009. Web. doi:10.1021/bi901150a.
Bailey, Lucas J, Fox, Brian G, & UW). Crystallographic and Catalytic Studies of the Peroxide-Shunt Reaction in a Diiron Hydroxylase. United States. https://doi.org/10.1021/bi901150a
Bailey, Lucas J, Fox, Brian G, and UW). Fri . "Crystallographic and Catalytic Studies of the Peroxide-Shunt Reaction in a Diiron Hydroxylase". United States. https://doi.org/10.1021/bi901150a.
@article{osti_1005929,
title = {Crystallographic and Catalytic Studies of the Peroxide-Shunt Reaction in a Diiron Hydroxylase},
author = {Bailey, Lucas J and Fox, Brian G and UW)},
abstractNote = {A diiron hydroxylase reaction typically begins by combination of O{sub 2} with a diferrous center to form reactive intermediates capable of hydrocarbon hydroxylation. In this natural cycle, reducing equivalents are provided by specific interactions with electron transfer proteins. The biological process can be bypassed by combining H{sub 2}O{sub 2} with a diferric center, i.e., peroxide-shunt catalysis. Here we show that toluene 4-monooxygenase has a peroxide-shunt reaction that is {approx}600-fold slower than catalysis driven by biological electron transfer. However, the toluene 4-monooxygenase hydroxylase-effector protein complex was stable in the presence of 300 mM H{sub 2}O{sub 2}, suggesting overall benign effects of the exogenous oxidant on active site structure and function. The X-ray structure of the toluene 4-monooxygenase hydroxylase-effector protein complex determined from crystals soaked in H{sub 2}O{sub 2} revealed a bound diatomic molecule, assigned to a cis-{mu}-1,2-peroxo bridge. This peroxo species resides in an active site position adjacent to the hydrogen-bonding substructure established by effector protein binding and faces into the distal cavity where substrate must bind during regiospecific aromatic ring hydroxylation catalysis. These results provide a new structural benchmark for how activated intermediates may be formed and dispatched during diiron hydroxylase catalysis.},
doi = {10.1021/bi901150a},
url = {https://www.osti.gov/biblio/1005929}, journal = {Biochemistry-US},
issn = {0006-2960},
number = (38) ; 09, 2009,
volume = 48,
place = {United States},
year = {2009},
month = {10}
}