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Characterization of the P450 2B6 genetic variant K262R for temperature stability and drug binding
Author(s) -
Talakad Jyothi C.,
Sun Ling,
Kumar Santosh,
Halpert James R.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.2_supplement.653
Subject(s) - cytochrome p450 , clopidogrel , drug metabolism , chemistry , raloxifene , pharmacology , drug , ic50 , ticlopidine , cyp2d6 , metabolism , medicine , biochemistry , estrogen receptor , in vitro , aspirin , cancer , breast cancer
Despite its relatively low expression in human liver, cytochrome P450 2B6 is a major catalyst of the metabolism of a number of clinically relevant drugs. P450 2B6 is also one of the most polymorphic human P450 enzymes, with the K262R variant being especially common. Prior studies have shown altered metabolism of several drugs by this variant. We created K262R in the P450 2B6dH background (N‐terminal modified and C‐ terminal His tagged) and expressed it in E. coli to study the effect of the Lys 262 →Arg substitution on P450 expression, stability, catalysis, and inhibition. Although K262R did not show altered P450 expression, the thermal stability ( T m ) was decreased by 2 °C, which might help explain discrepancies between activity and immunochemically‐determined protein levels in various samples. Furthermore, the effect on K262R of the potent P450 2B6 inhibitors clopidogrel, ticlopidine, raloxifene, sertraline, and clotrimazole was assessed. K262R showed a 6‐ and 2.5‐fold increased IC 50 with clopidogrel and ticlopidine, respectively, compared with P450 2B6dH. Most interestingly, K262R showed no inhibition by sertraline or raloxifene even at a concentration 35‐ and 5‐fold higher, respectively, than the IC 50 for P450 2B6dH. The results suggest that individuals, especially homozygotes, harboring K262R might be less susceptible to certain drug interactions. [NIH grant ES03619 and Center grant ES06676].