Mechanism-Based Inactivators as Probes of Cytochrome P450 Structure and Function

Authors: Kent U.M.; Jushchhyshyn M.I.; Hollenberg P.F.

Source: Current Drug Metabolism, Volume 2, Number 3, September 2001 , pp. 215-243(29)

Publisher: Bentham Science Publishers

Abstract:

The cytochromes P450 superfamily of enzymes is a group of hemeproteins That catalyze the metabolism of an extensive series of compounds including drugs, chemical carcinogens, fatty acids, and steroids. They oxidize substrates ranging in size from ethylene to cyclosporin. Although significant efforts have been made to obtain structural information on the active sites of the microbial P450s, relatively little is currently known regarding the identities of the critical amino acid residues in the P450 active sites that are involved in substrate binding and catalysis. Since information on the crystal structures of the eukaryotic P450s has been relatively limited, investigators have used a variety of other techniques in attempts to elucide the structural features that play a role in the catalytic properties and substrate specificity at the enzyme active site. These include site-directed mutagenesis, natural mutations, homology modeling, mapping with aryl-iron complexes, affinity and photoaffinity labeling, and mechanism-based inactivators. A variety of different mechanism-based inactivators have proven to be useful in identifiying active site amino acid residues involved in substrate binding and catalysis. In this review we present a sampling of the types of studies that can be conducted using mechanism-based inactivators and highlight studies with several classes of compounds including acetylenes, isothiocyanates, xanthates, aminobenzotriazoles, phencyclidine, and furanocoumarins. Labeled peptides isolated from the inactivated proteins have been analyzed by N-terminal amino acid sequencing in conjunction with mass spectrometry to determine the sites of covalent modification. Mechanistic studies aimed at identifying the basis for the inactivation following adduct formation are also presented.

Keywords: Cytochrome P450; homology modeling; Mapping; aminobenzotriazoles, phencyclidine; furanocoumarins; Acetylenes; isothiocyanates; xanthates; 2-ethynylnaphthalene; 9-ethynylphenanthrene

Language: English

Document Type: Review article

DOI: http://dx.doi.org/10.2174/1389200013338478

Publication date: 2001-09-01

• Current Drug Metabolism aims to cover all the latest and outstanding developments in drug metabolism and disposition. The journal serves as an international forum for the publication of timely reviews in drug metabolism. Current Drug Metabolism is an essential journal for academic, clinical, government and pharmaceutical scientists who wish to be kept informed and up-to-date with the latest and most important developments. The journal covers the following areas:
  
  In vitro systems including CYP-450; enzyme induction and inhibition; drug-drug interactions and enzyme kinetics; pharmacokinetics, toxicokinetics, species scaling and extrapolations; P-glycoprotein and transport carriers; target organ toxicity and interindividual variability; drug metabolism and disposition studies; extrahepatic metabolism; phase I and phase II metabolism; recent developments for the identification of drug metabolites and adducts.

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• In this Subject: Anatomy & Physiology ,  Pharmacology
• By this author: Kent U.M. ;  Jushchhyshyn M.I. ;  Hollenberg P.F.

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