Drennan C L, Matthews R G, Ludwig M L
Biophysics Research Division, University of Michigan, Ann Arbor 48109-1055.
Curr Opin Struct Biol. 1994 Dec;4(6):919-29. doi: 10.1016/0959-440x(94)90275-5.
Cobalamin-dependent methionine synthase is a large enzyme composed of structurally and functionally distinct regions. Recent studies have begun to define the roles of several regions of the protein. In particular, the structure of a 27 kDa cobalamin-binding fragment of the enzyme from Escherichia coli has been determined by X-ray crystallography, and has revealed the motifs and interactions responsible for recognition of the cofactor. The amino acid sequences of several adenosylcobalamin-dependent enzymes, the methylmalonyl coenzyme A mutases and glutamate mutases, show homology with the cobalamin-binding region of methionine synthase and retain conserved residues that are determinants for the binding of the prosthetic group, suggesting that these mutases and methionine synthase share common three-dimensional structures.
钴胺素依赖型甲硫氨酸合酶是一种由结构和功能不同的区域组成的大型酶。最近的研究已开始明确该蛋白质几个区域的作用。特别是，已通过X射线晶体学确定了来自大肠杆菌的该酶27 kDa钴胺素结合片段的结构，并揭示了负责辅因子识别的基序和相互作用。几种腺苷钴胺素依赖型酶，即甲基丙二酰辅酶A变位酶和谷氨酸变位酶的氨基酸序列，与甲硫氨酸合酶的钴胺素结合区域具有同源性，并保留了作为辅基结合决定因素的保守残基，这表明这些变位酶和甲硫氨酸合酶具有共同的三维结构。
