Tonozuka T, Ohtsuka M, Mogi S, Sakai H, Ohta T, Sakano Y
Department of Applied Biological Science, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Japan.
Biosci Biotechnol Biochem. 1993 Mar;57(3):395-401. doi: 10.1271/bbb.57.395.
Shimizu et al. and ourselves have reported some enzymatic properties of an alpha-amylase from Thermoactinomyces vulgaris R-47 that hydrolyzed pullulan to produce panose [M. Shimizu et al., Agric. Biol. Chem., 42, 1681-1688 (1978); Y. Sakano et al., Agric. Biol. Chem., 46, 1121-1129 (1982)]. In this study, we cloned a gene for an alpha-amylase, which was different from the one mentioned above but also hydrolyzed pullulan to produce panose, from T. vulgaris R-47, and analyzed the entire primary structure of the gene. We designated the previously reported enzyme as T. vulgaris alpha-amylase I (TVA I), and this novel enzyme as T. vulgaris alpha-amylase II (TVA II). The nucleotide sequence had an open reading frame of 1755 base pairs corresponding to a protein of 585 amino acid residues. Although this novel alpha-amylase, TVA II, hydrolyzed both pullulan and starch, the ratio of pullulan-hydrolyzing activity to starch-hydrolyzing activity of the enzyme was higher than that of TVA I, and the primary structure of the enzyme resembled neopullulanase, which scarcely hydrolyzed starch, rather than that of TVA I.
清水等人以及我们自己都报道过嗜热放线菌R - 47中一种α-淀粉酶的某些酶学性质，该酶能水解支链淀粉产生潘糖[M. 清水等人，《农业生物化学》，42，1681 - 1688(1978)；坂野洋等人，《农业生物化学》，46，1121 - 1129(1982)]。在本研究中，我们从嗜热放线菌R - 47中克隆了一种α-淀粉酶基因，它与上述基因不同，但同样能水解支链淀粉产生潘糖，并分析了该基因的完整一级结构。我们将先前报道的酶命名为嗜热放线菌α-淀粉酶I（TVA I），将这种新酶命名为嗜热放线菌α-淀粉酶II（TVA II）。核苷酸序列有一个1755个碱基对的开放阅读框，对应一个由585个氨基酸残基组成的蛋白质。尽管这种新的α-淀粉酶TVA II能水解支链淀粉和淀粉，但该酶水解支链淀粉的活性与水解淀粉的活性之比高于TVA I，并且该酶的一级结构与几乎不水解淀粉的新支链淀粉酶更相似，而不像TVA I的一级结构。
