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首页> 外文期刊>Environmental Science & Technology >Factors Affecting Phase I Stereoselective Biotransformation of Chiral Polychlorinated Biphenyls by Rat Cytochrome P-450 2B1 Isozyme
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Factors Affecting Phase I Stereoselective Biotransformation of Chiral Polychlorinated Biphenyls by Rat Cytochrome P-450 2B1 Isozyme

机译：大鼠细胞色素P-450 2B1同工酶影响手性多氯联苯I相立体选择性生物转化的因素

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摘要

In vitro incubations of rat cytochrome P-450 (CYP) 2B1 isozyme with three chiral polychlorinated biphenyl (PCB) congeners (PCBs 45, 95, and 132) were performed to investigate factors affecting phase I stereoselective biotransformation. Rat CYP2B1 preferentially biotransformed the second-eluting atropisomers of PCBs 45 and 95 at low substrate concentration ranges (≤ 15 μM). Biotransformation competition by different congeners was also observed, with increasing competition at higher chlorination. Competition decreased the biotransformation rates of each congener stereoselectively, affecting atropisomeric composition. No atropisomeric enrichment was observed for PCB 132 upon incubation of the racemate. However, under the same conditions, significant differences in biotransfbrmation kinetics were observed in individual atropisomer incubations, indicating that (+)-PCB 132 and (-)-PCB 132 were competi- tively biotransformed. Homology modeling and docking studies suggested that each atropisomer had different interactions with rat CYP2B1 and could dock with the isozyme at different locations. This is one possible explanation for stereoselective biotransfonnation and competition of chiral PCBs at the molecular level. Our results suggest that the lack of predictive capability for stereoselectrvity of PCBs and other chiral pollutants in biota may be due to competitive and/or inhibitory activities of different substrates, including individual enanbomers of the same compound.
机译：进行大鼠细胞色素P-450（CYP）2B1同工酶与三种手性多氯联苯（PCB）同系物（PCB 45、95和132）的体外温育，以研究影响I期立体选择性生物转化的因素。大鼠CYP2B1在低底物浓度范围（≤15μM）时优先对PCB 45和95的第二次洗脱阻转异构体进行生物转化。还观察到了由不同同源物进行的生物转化竞争，并且在较高氯化时竞争加剧。竞争选择性地降低了每个同类物的生物转化率，影响了阻转异构体组成。外消旋物孵育后未观察到PCB 132的阻转异构体富集。然而，在相同条件下，在单个阻转异构体孵育过程中观察到生物转移动力学的显着差异，这表明（+）-PCB 132和（-）-PCB 132是竞争性生物转化的。同源性建模和对接研究表明，每个阻转异构体与大鼠CYP2B1的相互作用不同，并且可以与同工酶在不同位置对接。这是分子水平上立体选择性生物转化和手性多氯联苯竞争的一种可能解释。我们的结果表明，对生物群中PCBs和其他手性污染物的立体选择性缺乏预测能力的原因可能是由于不同底物（包括同一化合物的单个螯合剂）的竞争和/或抑制活性。

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  • 来源
    《Environmental Science & Technology》 |2011年第19期|p.8298-8305|共8页
  • 作者

    Zhe Lu; Charles S. Wong;

  • 作者单位

    Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada;

    Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada,Richardson College for the Environment, Environmental Studies Program and Department of Chemistry, University of Winnipeg,Winnipeg, Manitoba R3B 2E9, Canada;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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