Document Detail

Functional characterization of cytochrome P450 2A6 allelic variants CYP2A6*15, CYP2A6*16, CYP2A6*21, and CYP2A6*22.
MedLine Citation:
PMID:  20139165     Owner:  NLM     Status:  MEDLINE    
Variation in CYP2A6 levels and activity can be attributed to genetic polymorphism and, thus, functional characterization of allelic variants is necessary to define the importance of CYP2A6 polymorphism in humans. The aim of the present study was to investigate the reported alleles CYP2A6*15, CYP2A6*16, CYP2A6*21, and CYP2A6*22, in terms of the functional consequences of their mutations on the enzyme catalytic activity. With use of the wild-type CYP2A6 cDNA as template, site-directed mutagenesis was performed to introduce nucleotide changes encoding K194E substitution in CYP2A6*15, R203S substitution in CYP2A6*16, K476R substitution in CYP2A6*21, and concurrent D158E and L160I substitutions in CYP2A6*22. Upon sequence verification, the CYP2A6 wild-type and mutant constructs were individually coexpressed with NADPH-cytochrome P450 reductase in Escherichia coli. A kinetic study using a coumarin 7-hydroxylase assay indicated that CYP2A6*15 exhibited higher V(max) than the wild type, whereas all mutant constructs, except for variant CYP2A6*16, exhibited higher K(m) values. Analysis of the V(max)/K(m) ratio revealed that all mutants demonstrated 0.85- to 1.05-fold differences from the wild type, with the exception of variant CYP2A6*22, which only portrayed 39% of the wild-type intrinsic clearance. These data suggested that individuals carrying the CYP2A6*22 allele are likely to have lower metabolism of CYP2A6 substrate than individuals expressing CYP2A6*15, CYP2A6*16, CYP2A6*21, and the wild type.
Kai Hung Tiong; Beow Chin Yiap; Eng Lai Tan; Rusli Ismail; Chin Eng Ong
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-02-05
Journal Detail:
Title:  Drug metabolism and disposition: the biological fate of chemicals     Volume:  38     ISSN:  1521-009X     ISO Abbreviation:  Drug Metab. Dispos.     Publication Date:  2010 May 
Date Detail:
Created Date:  2010-04-16     Completed Date:  2010-09-17     Revised Date:  2014-01-09    
Medline Journal Info:
Nlm Unique ID:  9421550     Medline TA:  Drug Metab Dispos     Country:  United States    
Other Details:
Languages:  eng     Pagination:  745-51     Citation Subset:  IM    
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MeSH Terms
Amino Acid Substitution / physiology
Aryl Hydrocarbon Hydroxylases / genetics*,  metabolism*
Base Sequence
Cell Membrane / metabolism
Coumarins / metabolism
Escherichia coli / genetics,  metabolism
Mutagenesis, Site-Directed
Polymorphism, Single Nucleotide / physiology*
Transformation, Genetic
Umbelliferones / metabolism
Reg. No./Substance:
0/Coumarins; 0/Umbelliferones; 93-35-6/7-hydroxycoumarin; A4VZ22K1WT/coumarin; EC 1.14.13.-/coumarin 7-hydroxylase; EC Hydrocarbon Hydroxylases

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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