Marsh E N, Leadlay P F
Department of Biochemistry, University of Cambridge, U.K.
Biochem J. 1989 Jun 1;260(2):339-43. doi: 10.1042/bj2600339.
Adenosylcobalamin-dependent methylmalonyl-CoA mutase from Propionibacterium shermanii contains no intramolecular disulphide bridges, but two of the six thiol groups in the heterodimer are only revealed after reduction of the denatured enzyme with dithiothreitol. The available evidence suggests that they are present in disulphide linkages to unknown thiols of low Mr. The two specifically masked cysteine residues are Cys-535 in the alpha-subunit and Cys-517 in the beta-subunit, which occupy exactly homologous positions in each chain.
来自谢氏丙酸杆菌的腺苷钴胺素依赖性甲基丙二酰辅酶A变位酶不含分子内二硫键，但在异源二聚体的六个巯基中，有两个只有在用二硫苏糖醇还原变性酶后才会暴露出来。现有证据表明，它们以二硫键的形式与低相对分子质量的未知硫醇相连。两个特异性被掩盖的半胱氨酸残基分别是α亚基中的Cys-535和β亚基中的Cys-517，它们在每条链中占据完全同源的位置。
