Mechanism of Flavoprotein <scp>l</scp>-6-Hydroxynicotine Oxidase: pH and Solvent Isotope Effects and Identification of Key Active Site Residues
作者:Paul F. Fitzpatrick、Fatemeh Chadegani、Shengnan Zhang、Vi Dougherty
DOI:10.1021/acs.biochem.6b01160
日期:2017.2.14
in ∼10-fold decreases in these parameters and a 6000-fold decrease in the kcat/Km value for oxygen. The shapes of the pH profiles are not altered by the N166A and Y311F mutations. There is no solvent isotope effect on the kcat/Km value for amines. The results are consistent with a model in which both the charged and neutral forms of the amine can bind, with the former rapidly losing a proton to a hydrogen
黄素酶1-6-羟基尼古丁氧化酶是单胺氧化酶家族的成员,在尼古丁的微生物分解代谢过程中催化( S )-6-羟基尼古丁氧化为6-羟基假氧尼古丁。虽然这种酶长期以来被认为可以催化碳-碳键的氧化,但最近显示它可以催化碳-氮键的氧化[Fitzpatrick, PF, et al. 2017]。 (2016)生物化学55 , 697–703]。 pH 值和活性位点残基诱变的影响现已被用来研究活性位点残基的机制和作用。 Asn166 和 Tyr311 与底物结合,而 Lys287 与黄素 N5 形成水介导的氢键。 N166A 和 Y311F 突变分别导致 ( S )-6-羟基尼古丁的k cat / K m和k red降低约 30 倍和约 4 倍,对 ( S )-6-羟基尼古丁的k cat / K m值影响更大)-6-羟基降烟碱。 K287M 突变导致这些参数下降约 10 倍,并且氧的k cat / K m值下降