色氨酸合酶
变构调节
吲哚试验
色氨酸
苏氨酸
化学
丝氨酸
生物化学
立体化学
生物合成
酶
ATP合酶
基质(水族馆)
结合位点
生物
氨基酸
生态学
作者
Andrew R. Buller,P. van Roye,Javier Murciano-Calles,Frances H. Arnold
出处
期刊:Biochemistry
[American Chemical Society]
日期:2016-12-13
卷期号:55 (51): 7043-7046
被引量:20
标识
DOI:10.1021/acs.biochem.6b01127
摘要
Tryptophan synthase (TrpS) catalyzes the final steps in the biosynthesis of l-tryptophan from l-serine (Ser) and indole-3-glycerol phosphate (IGP). We report that native TrpS can also catalyze a productive reaction with l-threonine (Thr), leading to (2S,3S)-β-methyltryptophan. Surprisingly, β-substitution occurs in vitro with a 3.4-fold higher catalytic efficiency for Ser over Thr using saturating indole, despite a >82000-fold preference for Ser in direct competition using IGP. Structural data identify a novel product binding site, and kinetic experiments clarify the atypical mechanism of specificity: Thr binds efficiently but decreases the affinity for indole and disrupts the allosteric signaling that regulates the catalytic cycle.
科研通智能强力驱动
Strongly Powered by AbleSci AI