Tanizawa K, Asano S, Masu Y, Kuramitsu S, Kagamiyama H, Tanaka H, Soda K
Institute for Chemical Research, Kyoto University, Japan.
J Biol Chem. 1989 Feb 15;264(5):2450-4.
The gene for thermostable D-amino acid aminotransferase from a thermophile, Bacillus species YM-1 was cloned and expressed efficiently in Escherichia coli. The entire covalent structure of the enzyme was determined from the nucleotide sequence of the cloned gene and mostly confirmed by amino acid sequences of tryptic peptides from the gene product. The polypeptide is composed of 282 amino acid residues with a calculated molecular weight of 32,226. Comparison of the primary structure with those of various proteins registered in a protein data bank revealed a significant sequence homology between D-amino acid aminotransferase and the L-branched chain amino acid aminotransferase of E. coli (Kuramitsu, S., Ogawa, T., Ogawa, H., and Kagamiyama, H. (1985) J. Biochem. (Tokyo) 97, 993-999); the active site lysyl residue is located in an equivalent position in both enzyme sequences of similar size. Despite the difference in subunit composition and no immunochemical cross-reactivity, the sequences of the two enzymes show similar hydropathy profiles, and spectrophotometric properties of the enzyme-bound cofactor are also similar. The sequence homology suggests that the structural genes for D-amino acid and L-branched chain amino acid aminotransferases evolved from a common ancestral gene.
来自嗜热芽孢杆菌属YM-1的耐热D-氨基酸转氨酶基因被克隆，并在大肠杆菌中高效表达。根据克隆基因的核苷酸序列确定了该酶的完整共价结构，并通过基因产物胰蛋白酶肽段的氨基酸序列进行了大部分确认。该多肽由282个氨基酸残基组成，计算分子量为32,226。将其一级结构与蛋白质数据库中登记的各种蛋白质的一级结构进行比较，发现D-氨基酸转氨酶与大肠杆菌的L-支链氨基酸转氨酶之间存在显著的序列同源性（仓光，S.，小川，T.，小川，H.，和加美山，H.（1985年）《生物化学杂志》（东京）97，993 - 999）；活性位点赖氨酰残基位于两种大小相似的酶序列中的等效位置。尽管亚基组成不同且无免疫化学交叉反应，但两种酶的序列显示出相似的亲水性图谱，并且酶结合辅因子的分光光度性质也相似。序列同源性表明D-氨基酸和L-支链氨基酸转氨酶的结构基因起源于一个共同的祖先基因。
