Covalent modification of subtilisin Bacillus lentus Cysteine mutants with enantiomerically pure chiral auxiliaries causes remarkable changes in activity
作者:Michael Dickman、J.Bryan Jones
DOI:10.1016/s0968-0896(00)00121-8
日期:2000.8
used to introduce virtually unlimited structural modifications in enzymes via reaction with the thiol group of cysteine. The covalent coupling of enantiomerically pure (R) and (S) chiral auxiliary methanethiosulfonate ligands to cysteine mutants of subtilisin Bacillus lentus induces spectacular changes in catalytic activity between diastereomeric enzymes. Amidase and esterase kinetic assays using a low
甲硫代磺酸盐试剂可用于通过与半胱氨酸的巯基反应,在酶中引入几乎无限的结构修饰。对映体纯的(R)和(S)手性辅助甲硫代磺酸盐配体与枯草杆菌蛋白酶芽孢杆菌的半胱氨酸突变体的共价偶联引起非对映异构酶之间催化活性的显着变化。使用低底物近似值进行的酰胺酶和酯酶动力学测定用于建立化学修饰突变体的kcat / KM值,并且发现非对映异构酶之间的活性差异高达3倍。通过亚甲基单元改变连接苯基或苄基恶唑烷酮配体与突变体N62C的碳链的长度,可以逆转非对映异构酶的活性。同样,在S166C处从苯基恶唑烷酮配体变为苄基恶唑烷酮配体可逆转非对映异构酶的活性。S166C和L217C的手性修饰使CMM既具有高酯酶kcat / KM值,又具有高酯酶与酰胺酶之比,且非对映异构酶之间存在较大差异。