De Biase D, Maras B, Bossa F, Barra D, John R A
Dipartimento di Scienze Biochimiche A. Rossi Fanelli, Università La Sapienza, Roma, Italy.
Eur J Biochem. 1992 Sep 1;208(2):351-7. doi: 10.1111/j.1432-1033.1992.tb17193.x.
The amino acid sequence of pig liver 4-aminobutyrate aminotransferase has been determined by gas-phase sequencing of proteolytically derived peptide fragments. The sequence differs substantially from that predicted for the same enzyme on the basis of the sequence of cDNA derived from pig brain in recently published work [Kwon, O., Park, J. & Churchich, J. E. (1992) J. Biol. Chem. 267, 7215-7216]. Apart from a few minor differences, the two sequences are completely different in the segment of protein comprising the 36 residues at positions 107-142. Insertion of a cytosine between bases 402 and 403 in the cDNA sequence, together with deletion of the guanine at position 510, results in a DNA sequence which predicts exactly the amino acid sequence determined by peptide analysis in the present work. The mammalian enzyme has approximately 44% sequence identity with the same enzyme from two unicellular eukaryotes (Saccharomyces cerevisiae, Aspergillus nidulans) and 22% identity with that from Escherichia coli.
通过对猪肝脏4-氨基丁酸转氨酶经蛋白酶水解产生的肽片段进行气相测序，确定了其氨基酸序列。在最近发表的研究中，根据从猪脑获得的cDNA序列预测的该酶序列，与本研究中的序列存在显著差异[Kwon, O., Park, J. & Churchich, J. E. (1992) J. Biol. Chem. 267, 7215 - 7216]。除了一些细微差异外，在包含第107 - 142位36个残基的蛋白质片段中，这两个序列完全不同。cDNA序列中第402和403位碱基之间插入一个胞嘧啶，同时删除第510位的鸟嘌呤，得到的DNA序列恰好预测了本研究中通过肽分析确定的氨基酸序列。该哺乳动物酶与来自两种单细胞真核生物（酿酒酵母、构巢曲霉）的同一种酶具有约44%的序列同一性，与来自大肠杆菌的该酶具有22%的同一性。
