Stereochemistry of reactions of the inhibitor/substrates l- and d-β-chloroalanine with β-mercaptoethanol catalysed by l-aspartate aminotransferase and d-amino acid aminotransferase respectively
作者:Benjamin Adams、Kreingkrai Lowpetch、Faye Thorndycroft、Sheena M. Whyte、Douglas W. Young
DOI:10.1039/b508199h
日期:——
Two members of the α-family of PLP-dependent enzymes, L-aspartate aminotransferase and D-amino acid aminotransferase, have been shown to catalyse β-substitution of L- and D-β-chloroalanine respectively with β-mercaptoethanol, reactions typical of the β-family of PLP-dependent enzymes. The reaction catalysed by L-aspartate aminotransferase has been shown to occur with retention of stereochemistry, a typical outcome for reactions catalysed by β-family enzymes. There are also indications that the reaction catalysed by D-amino acid aminotransferase may involve retention of stereochemistry. Both enzymes have been shown to catalyse exchange at C-3 when the appropriate enantiomer of β-chloroalanine is the substrate.
两种α家族的PLP依赖性酶,L-天冬氨酸氨基转移酶和D-氨基酸氨基转移酶,已被证明分别能催化L-和D-β-氯丙氨酸与β-巯基乙醇的β取代反应,这些反应是β家族PLP依赖性酶的典型特征。已显示L-天冬氨酸氨基转移酶催化的反应发生时保持立体化学,这是β家族酶催化反应的典型结果。还有迹象表明,D-氨基酸氨基转移酶催化的反应也可能涉及立体化学的保持。当适当的β-氯丙氨酸的对映体作为底物时,这两种酶已被证明能在C-3位催化交换反应。