Sugio S, Petsko G A, Manning J M, Soda K, Ringe D
Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02254, USA.
Biochemistry. 1995 Aug 1;34(30):9661-9. doi: 10.1021/bi00030a002.
The three-dimensional structure of D-amino acid aminotransferase (D-AAT) in the pyridoxamine phosphate form has been determined crystallographically. The fold of this pyridoxal phosphate (PLP)-containing enzyme is completely different from those of any of the other enzymes that utilize PLP as part of their mechanism and whose structures are known. However, there are some striking similarities between the active sites of D-AAT and the corresponding enzyme that transaminates L-amino acids, L-aspartate aminotransferase. These similarities represent convergent evolution to a common solution of the problem of enforcing transamination chemistry on the PLP cofactor. Implications of these similarities are discussed in terms of their possible roles in the stabilization of intermediates of a transamination reaction. In addition, sequence similarity between D-AAT and branched chain L-amino acid aminotransferase suggests that this latter enzyme will also have a fold similar to that of D-AAT.
已通过晶体学方法确定了磷酸吡哆胺形式的D-氨基酸转氨酶（D-AAT）的三维结构。这种含磷酸吡哆醛（PLP）的酶的折叠方式与任何其他利用PLP作为其机制一部分且结构已知的酶完全不同。然而，D-AAT的活性位点与催化L-氨基酸转氨作用的相应酶L-天冬氨酸转氨酶之间存在一些显著的相似性。这些相似性代表了在PLP辅因子上进行转氨化学作用这一问题的共同解决方案的趋同进化。根据这些相似性在转氨反应中间体稳定化中可能发挥的作用对其意义进行了讨论。此外，D-AAT与支链L-氨基酸转氨酶之间的序列相似性表明，后一种酶的折叠方式也将与D-AAT相似。
