Lakhman Sukhwinder S, Ghosh Debashis, Blanco Javier G
Department of Pharmaceutical Sciences, The State University of New York at Buffalo, 545 Cooke Hall, Buffalo, NY 14260-1200, USA.
Drug Metab Dispos. 2005 Feb;33(2):254-7. doi: 10.1124/dmd.104.002006. Epub 2004 Nov 10.
Human carbonyl reductase (CBR) activity accounts for a significant fraction of the metabolism of endogenous and xenobiotic carbonyl compounds. It is possible that genetic polymorphisms in CBR1 and CBR3 are key for the wide interindividual variability in the disposition of CBR drug substrates. We pinpointed a single nucleotide polymorphism in CBR3 (CBR3 V244M) that encodes for a V244 to M244 change. Blacks showed a higher frequency of the M244 allele (q = 0.51, n = 49) than did whites (q = 0.31, n = 70; p = 0.003). In addition, DNA variation panels from 10 ethnic groups presented a wide range of CBR3 V244M genotype distributions. Kinetic experiments with the recombinant CBR3 protein variants and menadione revealed that CBR3 M244 has significantly higher V(max) than does CBR3 V244 (V(max) CBR3 M244 = 40.6 +/- 1.3 micromol/min x mg versus V(max) CBR3 V244 = 19.6 +/- 2.0 micromol/min x mg, p = 0.002). In contrast, both isoforms presented similar K(m) values (K(m) CBR3 M244 = 22.9 +/- 2.9 microM versus K(m) CBR3 V244 = 24.6 +/- 3.2 microM, p = 0.43). Assays with NADP(H) demonstrated a higher V(maxNADP(H)) (1.6-fold) and increased catalytic efficiency (V(maxNADP(H))/K(mNADP(H))) for CBR3 M244 compared with CBR3 V244 (p = 0.013). Comparative three-dimensional analyses based on the structure of the homologous porcine carbonyl reductase suggested that the V244M substitution is positioned in a region critical for interactions with the NADP(H) cofactor. These studies demonstrate that the common CBR3 V244M polymorphism encodes for CBR3 isoforms with distinctive enzymatic properties.
人类羰基还原酶（CBR）活性在内源性和外源性羰基化合物的代谢中占很大一部分。CBR1和CBR3中的基因多态性可能是CBR药物底物处置中个体间广泛差异的关键。我们确定了CBR3中的一个单核苷酸多态性（CBR3 V244M），它编码V244到M244的变化。黑人中M244等位基因的频率（q = 0.51，n = 49）高于白人（q = 0.31，n = 70；p = 0.003）。此外，来自10个种族群体的DNA变异面板呈现出广泛的CBR3 V244M基因型分布。用重组CBR3蛋白变体和甲萘醌进行的动力学实验表明，CBR3 M244的V(max)显著高于CBR3 V244（CBR3 M244的V(max)= 40.6 +/- 1.3微摩尔/分钟×毫克，而CBR3 V244的V(max)= 19.6 +/- 2.0微摩尔/分钟×毫克，p = 0.002）。相比之下，两种同工型呈现出相似的K(m)值（CBR3 M244的K(m)= 22.9 +/- 2.9微摩尔，而CBR3 V244的K(m)= 24.6 +/- 3.2微摩尔，p = 0.43）。用NADP(H)进行的测定表明，与CBR3 V244相比，CBR3 M244的V(maxNADP(H))更高（高1.6倍），催化效率（V(maxNADP(H))/K(mNADP(H))）增加（p = 0.013）。基于同源猪羰基还原酶结构的比较三维分析表明，V244M取代位于与NADP(H)辅因子相互作用的关键区域。这些研究表明，常见的CBR3 V244M多态性编码具有独特酶学性质的CBR3同工型。
