Laboratory of Protein Evolution, Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 84551, Bratislava, Slovakia,
Cell Mol Life Sci. 2014 Apr;71(7):1149-70. doi: 10.1007/s00018-013-1388-z. Epub 2013 Jun 27.
α-Amylase (EC 3.2.1.1) represents the best known amylolytic enzyme. It catalyzes the hydrolysis of α-1,4-glucosidic bonds in starch and related α-glucans. In general, the α-amylase is an enzyme with a broad substrate preference and product specificity. In the sequence-based classification system of all carbohydrate-active enzymes, it is one of the most frequently occurring glycoside hydrolases (GH). α-Amylase is the main representative of family GH13, but it is probably also present in the families GH57 and GH119, and possibly even in GH126. Family GH13, known generally as the main α-amylase family, forms clan GH-H together with families GH70 and GH77 that, however, contain no α-amylase. Within the family GH13, the α-amylase specificity is currently present in several subfamilies, such as GH13_1, 5, 6, 7, 15, 24, 27, 28, 36, 37, and, possibly in a few more that are not yet defined. The α-amylases classified in family GH13 employ a reaction mechanism giving retention of configuration, share 4-7 conserved sequence regions (CSRs) and catalytic machinery, and adopt the (β/α)8-barrel catalytic domain. Although the family GH57 α-amylases also employ the retaining reaction mechanism, they possess their own five CSRs and catalytic machinery, and adopt a (β/α)7-barrel fold. These family GH57 attributes are likely to be characteristic of α-amylases from the family GH119, too. With regard to family GH126, confirmation of the unambiguous presence of the α-amylase specificity may need more biochemical investigation because of an obvious, but unexpected, homology with inverting β-glucan-active hydrolases.
α-淀粉酶（EC 3.2.1.1）是最著名的淀粉酶。它催化淀粉和相关α-葡聚糖中α-1,4-糖苷键的水解。一般来说，α-淀粉酶是一种具有广泛底物偏好和产物特异性的酶。在所有糖基水解酶（GH）的基于序列的分类系统中，它是最常出现的糖苷水解酶之一。α-淀粉酶是 GH13 家族的主要代表，但它可能也存在于 GH57 和 GH119 家族中，甚至可能存在于 GH126 家族中。通常被称为主要α-淀粉酶家族的 GH13 家族与 GH70 和 GH77 家族一起形成 GH-H 家族，但后两者不含α-淀粉酶。在 GH13 家族中，α-淀粉酶特异性目前存在于几个亚家族中，如 GH13_1、5、6、7、15、24、27、28、36、37，并且可能还有一些尚未定义的亚家族。分类在 GH13 家族中的α-淀粉酶采用保留构型的反应机制，共享 4-7 个保守序列区（CSRs）和催化机制，并采用（β/α）8-桶催化结构域。尽管 GH57 家族的α-淀粉酶也采用保留反应机制，但它们具有自己的五个 CSRs 和催化机制，并采用（β/α）7-桶折叠。这些 GH57 家族的特征可能也是 GH119 家族的α-淀粉酶的特征。关于 GH126 家族，由于与反转β-葡聚糖活性水解酶明显但意外的同源性，可能需要更多的生化研究来确认α-淀粉酶特异性的明确存在。
