点击次数：

论文类型：期刊论文

发表时间：2008-05-01

发表刊物：BIOTECHNOLOGY LETTERS

收录刊物：SCIE、EI、PubMed

卷号：30

期号：5

页面范围：869-875

ISSN号：0141-5492

关键字：azoreductase; flavodoxin; nitroreductase; Rhodobacter sphaeroides; site-directed mutagenesis

摘要：Comparison of three-dimensional structures of flavin-dependent azoreductases revealed two conserved loops around the flavin mononucleotide (FMN) cofactor. Tyr74, His75 and Lys109 in the two loops of azoreductase AZR from Rhodobacter sphaeroides were replaced with Trp, Asn and Ala/His by site-directed mutagenesis, respectively. The optimal pH values of K109H and H75N were pH 6, and those of K109A and Y74W were pH 9. The optimal temperature (30 degrees C) was not affected by mutation. Positively charged residues at position 109 is critical for the binding of methyl red. K109 might only be involved in the binding of the 2'-phosphate group of NADPH and have no effect on the binding of NADH. Y74W and H75N mutations decreased the binding of methyl red/nitrofurazone and had no affect on the binding of NADPH.