Battchikova N, Himanen J P, Ahjolahti M, Korpela T
Finnish-Russian Joint Biotechnology Laboratory, Department of Biochemistry, University of Turku, Finland.
Biochim Biophys Acta. 1996 Jul 18;1295(2):187-94. doi: 10.1016/0167-4838(96)00039-8.
Two peaks of aspartate aminotransferase (AspAT) catalytic activity were observed during DEAE chromatography of a protein extract from alkalophilic B. circulans. The enzyme purified from the major peak appeared to be not aspartate but phosphoserine aminotransferase (PSAT) with a considerably high AspAT side activity. The sequence of the enzyme N-terminus was determined, and the PSAT gene was cloned as two separate fragments. DNA sequencing revealed the open reading frame for the PSAT starting from TTG, putative ribosomal binding site and terminator of transcription. The PSAT gene encodes a protein of 361 amino acids (M(r) 39793) which shows moderate homology to other known phosphoserine aminotransferases (36-46% of identity, 60-64% of similarity). The PSAT from the alkalophile shares with all of them the consensus sequence pattern around the pyridoxal 5'-phosphate attachment site.
在嗜碱环状芽孢杆菌的蛋白质提取物进行DEAE色谱分析过程中，观察到了天冬氨酸转氨酶（AspAT）催化活性的两个峰值。从主峰纯化得到的酶似乎不是天冬氨酸转氨酶，而是磷酸丝氨酸转氨酶（PSAT），其具有相当高的AspAT副活性。测定了该酶N端的序列，并将PSAT基因克隆为两个单独的片段。DNA测序揭示了从TTG开始的PSAT的开放阅读框、假定的核糖体结合位点和转录终止子。PSAT基因编码一种由361个氨基酸组成的蛋白质（M(r) 39793），它与其他已知的磷酸丝氨酸转氨酶具有适度的同源性（同一性为36 - 46%，相似性为60 - 64%）。嗜碱菌中的PSAT与所有这些酶在磷酸吡哆醛5'-磷酸附着位点周围具有共同的序列模式。
