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Title: Freeze-quenched iron-oxo intermediates in cytochromes P450

Abstract

Since the discovery of cytochromes P450 and their assignment to heme proteins a reactive iron-oxo intermediate as the hydroxylating species has been discussed. It is believed that the electronic structure of this intermediate corresponds to an iron(IV)-porphyrin-{pi}-cation radical system (Compound I). To trap this intermediate the reaction of P450 with oxidants (shunt pathway) has been used. The common approaches are stopped-flow experiments with UV-visible spectroscopic detection or rapid-mixing/freeze-quench studies with EPR and Moessbauer spectroscopic characterization of the trapped intermediate. Surprisingly, the two approaches seem to give conflicting results. While the stopped-flow data indicate the formation of a porphyrin-{pi}-cation radical, no such species is seen by EPR spectroscopy, although the Moessbauer data indicate iron(IV) for P450cam (CYP101) and P450BMP (CYP102). Instead, radicals on tyrosine and tryptophan residues are observed. These findings are reviewed and discussed with respect to intramolecular electron transfer from aromatic amino acids to a presumably transiently formed porphyrin-{pi}-cation radical.

Authors:
 [1];  [2];  [3]
  1. Max-Delbrueck-Center for Molecular Medicine, 13125 Berlin (Germany). E-mail: christiane_jung@hotmail.com
  2. Technical University of Kaiserslautern, Department of Physics, 67663 Kaiserslautern (Germany)
  3. Max-Volmer Laboratory for Biophysical Chemistry, Technical University Berlin, PC 14, 10623 Berlin (Germany)
Publication Date:
OSTI Identifier:
20793202
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.2005.08.166; PII: S0006-291X(05)01878-4; 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; CATIONS; CYTOCHROMES; ELECTRON SPIN RESONANCE; ELECTRON TRANSFER; ELECTRONIC STRUCTURE; HEME; IRON; MOESSBAUER EFFECT; OXIDIZERS; RADICALS; SPECTROSCOPY; TRYPTOPHAN; TYROSINE

Citation Formats

Jung, Christiane, Schuenemann, Volker, and Lendzian, Friedhelm. Freeze-quenched iron-oxo intermediates in cytochromes P450. United States: N. p., 2005. Web. doi:10.1016/J.BBRC.2005.0.
Jung, Christiane, Schuenemann, Volker, & Lendzian, Friedhelm. Freeze-quenched iron-oxo intermediates in cytochromes P450. United States. doi:10.1016/J.BBRC.2005.0.
Jung, Christiane, Schuenemann, Volker, and Lendzian, Friedhelm. Fri . "Freeze-quenched iron-oxo intermediates in cytochromes P450". United States. doi:10.1016/J.BBRC.2005.0.
@article{osti_20793202,
title = {Freeze-quenched iron-oxo intermediates in cytochromes P450},
author = {Jung, Christiane and Schuenemann, Volker and Lendzian, Friedhelm},
abstractNote = {Since the discovery of cytochromes P450 and their assignment to heme proteins a reactive iron-oxo intermediate as the hydroxylating species has been discussed. It is believed that the electronic structure of this intermediate corresponds to an iron(IV)-porphyrin-{pi}-cation radical system (Compound I). To trap this intermediate the reaction of P450 with oxidants (shunt pathway) has been used. The common approaches are stopped-flow experiments with UV-visible spectroscopic detection or rapid-mixing/freeze-quench studies with EPR and Moessbauer spectroscopic characterization of the trapped intermediate. Surprisingly, the two approaches seem to give conflicting results. While the stopped-flow data indicate the formation of a porphyrin-{pi}-cation radical, no such species is seen by EPR spectroscopy, although the Moessbauer data indicate iron(IV) for P450cam (CYP101) and P450BMP (CYP102). Instead, radicals on tyrosine and tryptophan residues are observed. These findings are reviewed and discussed with respect to intramolecular electron transfer from aromatic amino acids to a presumably transiently formed porphyrin-{pi}-cation radical.},
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}
}
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