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论文类型：期刊论文

发表时间：2008-09-01

发表刊物：APPLIED MICROBIOLOGY AND BIOTECHNOLOGY

收录刊物：SCIE、EI、PubMed、Scopus

卷号：80

期号：3

页面范围：409-416

ISSN号：0175-7598

关键字：quinone reductase; azoreductase; oxidative stress; heat shock; survival

摘要：Quinone reductase activity of azoreductase AZR from Rhodobacter sphaeroides was reported. High homologies were found in the cofactor/substrate-binding regions of quinone reductases from different domains. 3D structure comparison revealed that AZR shared a common overall topology with mammal NAD(P)H/quinone oxidoreductase NQO1. With menadione as substrate, the optimal pH value and temperature were pH 8-9 and 50 degrees C, respectively. Following the ping-pong kinetics, AZR transferred two electrons from NADPH to quinone substrate. It could reduce naphthoquinones and anthraquinones, such as menadione, lawsone, anthraquinone-2-sulfonate, and anthraquinone-2,6-disulfonate. However, no activity was detected with 1,4-benzoquinone. Dicoumarol competitively inhibited AZR's quinone reductase activity with respect to NADPH, with an obtained K-i value of 87.6 mu M. Significantly higher survival rates were obtained in Escherichia coli YB overexpressing AZR than in the control strain when treated by heat shock and oxidative stressors such as H2O2 and menadione.