A Single Nucleotide Polymorphism of CYP2B6 Found in Japanese Enhances Catalytic Activity by Autoactivation

doi:10.1006/bbrc.2001.4524

Biochemical and Biophysical Research Communications

Volume 281, Issue 5, 16 March 2001, Pages 1256-1260

https://doi.org/10.1006/bbrc.2001.4524 Get rights and content

Abstract

A single nucleotide polymorphism (SNP) resulting in a substitution from Gln to His was found in exon 4 of the CYP2B6 gene in Japanese. The frequency of the variant allele was found to be 19.9%. The mutant- and the wild-type enzymes were expressed in Escherichia coli, and the effects of the single amino acid substitution on the catalytic activity were examined by investigating the kinetic profiles of 7-ethoxycoumarin O-deethylase activity. The wild-type enzyme showed typical Michaelis–Menten kinetics, while the mutant-type enzyme represented the sigmoidal kinetics with a higher V_max value compared to that of the wild-type enzyme. Eadie–Hofstee plots further revealed an existence of allosteric effects for the reaction catalyzed by the variant. This is the first evidence demonstrating that only one amino acid substitution, Gln172His, caused by natural SNP enhances the catalytic activity of CYP by obtaining the character of homotropic cooperativity.

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Citation Excerpt :
This suggests the slight change in bulkiness of the critical amino acid to mainly perturb productive orientation of the substrate toward the iron-oxene species. Moreover, a single nucleotide polymorphism (SNP) causing a glutamine → histidine exchange at position 172 of the CYP2B6*9 allelic variant was shown to induce a sigmoidal kinetic profile when testing the activity of 7-ethoxycoumarin (7EC) O-deethylation; this was interpreted to be suggestive of homotropic autoactivation of the enzyme by 7EC to provoke an increase in the Vmax value [72]. This catalytically relevant replacement of the neutral glutamine by the basic histidine takes place at a structural location assignable to the E-helical surface domain remote from any of the six known substrate recognition sites (SRSs).
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^☆: Abbreviations used: CYP, cytochrome P450; dNTP, deoxynucleotide 5′-triphosphates; PCR–SSCP, polymerase chain reaction–single-strand conformation polymorphism; RFLP, restriction fragment length polymorphism; SNP, single nucleotide polymorphism; SRS, substrate recognition site.

¹: To whom correspondence and reprint requests should be addressed at Laboratory of Drug Metabolism, Graduate School of Pharmaceutical Sciences, Hokkaido University, N12W6, Kita-ku, Sapporo, 060-0812, Japan. Fax: +81-11-706-4978. E-mail: [email protected].

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Regular ArticleA Single Nucleotide Polymorphism of CYP2B6 Found in Japanese Enhances Catalytic Activity by Autoactivation☆

Abstract

Biochem. Pharmacol.

Biochem. Pharmacol.

Arch. Biochem. Biophys.

J. Biol. Chem.

Anal. Biochem.

Cancer Res.

Drug Metab. Dispos.

J. Pharmacol. Exp. Ther.

Xenobiotica

Drug Metab. Dispos.

Drug Metab. Dispos.

Br. J. Clin. Pharmacol.

Drug Metab. Dispos.

Anesthesiology

Regular Article
A Single Nucleotide Polymorphism of CYP2B6 Found in Japanese Enhances Catalytic Activity by Autoactivation☆