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Titolo:
Structure-function analysis of human cytochrome P450 3A4 using 7-alkoxycoumarins as active-site probes
Autore:
Khan, KK; Halpert, JR;
Indirizzi:
Univ Texas, Med Branch, Dept Pharmacol & Toxicol, Galveston, TX 77555 USA Univ Texas Galveston TX USA 77555 acol & Toxicol, Galveston, TX 77555 USA
Titolo Testata:
ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS
fascicolo: 2, volume: 373, anno: 2000,
pagine: 335 - 345
SICI:
0003-9861(20000115)373:2<335:SAOHCP>2.0.ZU;2-0
Fonte:
ISI
Lingua:
ENG
Soggetto:
SUBSTRATE RECOGNITION SITES; ESCHERICHIA-COLI EXPRESSION; HUMAN LIVER-MICROSOMES; ALPHA-NAPHTHOFLAVONE; DIRECTED MUTAGENESIS; O-DEALKYLASE; WILD-TYPE; METABOLISM; ACTIVATION; ENZYMES;
Keywords:
cytochrome P450 3A4; 7-alkoxycoumarin; computer modeling; enzymatic constrains; electronic influence;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
42
Recensione:
Indirizzi per estratti:
Indirizzo: Khan, KK Univ Texas, Med Branch, Dept Pharmacol & Toxicol, Route 1031,301 Univ Blvd, Galveston, TX 77555 USA Univ Texas Route 1031,301 Univ Blvd Galveston TX USA 77555 55 USA
Citazione:
K.K. Khan e J.R. Halpert, "Structure-function analysis of human cytochrome P450 3A4 using 7-alkoxycoumarins as active-site probes", ARCH BIOCH, 373(2), 2000, pp. 335-345

Abstract

The oxidation of a series of seven alkyl ethers of 7-hydroxycoumarin by cytochrome P450 3A4 (CYP3A4) has been studied to probe the active site of theenzyme. TLC of the reaction mixture showed formation of metabolites other than 7-hydroxycoumarin, The separation and characterization of the different metabolites of the C4 to C7 compounds were achieved using a combination of TLC, HPLC, and gas chromatography-electron impact mass spectra, Among the7-alkoxycoumarins, 7-hexoxycoumarin was found to be the most suitable candidate for investigating the active site of cytochrome CYP3A4, due to the well-separated metabolite peaks on TLC and HPLC, 7-Hexoxycoumarin was found to produce three side-chain hydroxylated products besides 7-hydroxycoumarin:7-(5-hydroxyhexoxy)coumarin, 7-(4-hydroxyhexoxy)coumarin, and 7-(3-hydroxycoumarin), The substitution of residues from substrate recognition sites -1, -4, -5, and -6 of CYP3A4 showed a strong influence on the product profileof 7-hexoxycoumarin, the most prominent effects observed with mutants at residues 119, 301, 305, 370, 373, and 479, The docking of 7-hexoxycoumarin into a molecular model of CYP3A4 also confirmed the presence of these residues within 5 A of the substrate. A comparative study of cytochrome P450 2B1 showed that the active-site mutants F206L, T302V, V363A, and 54780 but not V363L exhibited a dramatic decrease in total 7-hexoxycoumarin hydroxylation, The study suggests that although the electronic nature of the substrate is important, enzymatic constraints significantly contribute to CYP3A4 selectivity. (C) 2000 Academic Press.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 20/01/20 alle ore 04:52:30