Redesign of enzyme for improving catalytic activity and enantioselectivity toward poor substrates: manipulation of the transition state
作者:Tadashi Ema、Yasuko Nakano、Daiki Yoshida、Shusuke Kamata、Takashi Sakai
DOI:10.1039/c2ob25614b
日期:——
altered the transition state. Substrate mapping analysis strongly suggested that the CH/π interaction partly enhanced the (R)-enantiomer reactivity, the estimated energy of the CH/π interaction being −0.4 kcal mol−1. The substrate scope of the I287F/I290A double mutant was broad. This biocatalyst was useful for the dynamic kinetic resolution of a variety of bulky secondary alcohols for which the wild-type
对于大多数脂肪酶而言,在羟基的两侧均具有大的取代基的仲醇固有地是较差的底物。鉴于这种弱点,我们重新设计了洋葱伯克霍尔德氏菌脂肪酶,以创建具有改善的酶促特性的变体。对于野生型酶显示低转化率和低E值的不良底物,I287F / I290A双突变体显示出高转化率和E值(> 200)(5)。该变体的催化活性和对映体选择性的增强是由于两个突变的协同作用引起的:Phe287既有助于增强(R)-对映异构体反应性,又可以抑制(S)-对映体的反应性,而Ala290则为促进(R)-对映体的酰化创造了空间。动力学常数表明突变有效地改变了过渡状态。底物作图分析强烈表明,CH /π相互作用部分增强了(R)-对映异构体的反应性,CH /π相互作用的估计能量为-0.4 kcal mol -1。I287F / I290A双突变体的底物范围很广。这种生物催化剂可用于动态动力学拆分各种大体积的仲醇,而野生型酶几乎没有或没有活性。