中文摘要：由于饲料所存在的不可避免的污染，生猪很容易暴露于黄曲霉毒素B1（AFB1）并因此中毒，中毒的猪肉制品可能进而影响人体健康。迄今为止，生猪体内AFB1的代谢过程，尤其是主要负责其激活的细胞色素P450氧化酶，仍有待澄清。本研究从猪肝中克隆了CYP3A29，并将其在大肠杆菌中表达，还用典型的P450 CO差光谱特征和硝苯地平氧化活性证实了其活性。本研究结果证明了猪CYP3A29对体外AFB1的生物活化作用，并为CYP3A29 对AFB1的区域选择性提供了参考。
外文摘要：Due to unavoidable contaminations in feedstuff, pigs are easily exposed to aflatoxin B1 (AFB1) and suffer from poisoning, thus the poisoned products potentially affect human health. Heretofore, the metabolic process of AFB1 in pigs remains to be clarified, especially the principal cytochrome P450 oxidases responsible for its activation. In this study, we cloned CYP3A29 from pig liver and expressed it in Escherichia coli, and its activity has been confirmed with the typical P450 CO-reduced spectral characteristic and nifedipine-oxidizing activity. The reconstituted membrane incubation proved that the recombinant CYP3A29 was able to oxidize AFB1 to form AFB1-exo-8,9-epoxide in vitro. The structural basis for the regioselective epoxidation of AFB1 by CYP3A29 was further addressed. The T309A mutation significantly decreased the production of AFBO, whereas F304A exhibited an enhanced activation towards AFB1. In agreement with the mutagenesis study, the molecular docking simulation suggested that Thr309 played a significant role in stabilization of AFB1 binding in the active center through a hydrogen bond. In addition, the bulk phenyl group of Phe304 potentially imposed steric hindrance on the binding of AFB1. Our study demonstrates the bioactivation of pig CYP3A29 towards AFB1 in vitro, and provides the insight for understanding regioselectivity of CYP3A29 to AFB1.
外文关键词：htochrome P450；CYP3A29；AFB(1)；bioactivation；regioselectivity
作者：Wu, Jun; Chen, Ruohong; Zhang, Caihui; Li, Kangbai; Xu, Weiying; Wang, Lijuan; Chen, Qingmei; Mu, Peiqiang; Jiang, Jun; Wen, Jikai; Deng, Yiqun
作者单位：华南农业大学
期刊名称：TOXINS
期刊影响因子：3.571
出版年份：2016
出版刊次：9
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