Rodríguez-Sanoja Romina, Oviedo Norma, Sánchez Sergio
Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, A. P. 70228. Universidad Nacional Autónoma de México, México DF 04510, Mexico.
Curr Opin Microbiol. 2005 Jun;8(3):260-7. doi: 10.1016/j.mib.2005.04.013.
Glucosidic bonds from different non-soluble polysaccharides such as starch, cellulose and xylan are hydrolyzed by amylases, cellulases and xylanases, respectively. These enzymes are produced by microorganisms. They have a modular structure that is composed of a catalytic domain and at least one non-catalytic domain that is involved in polysaccharide binding. Starch-binding modules are present in microbial enzymes that are involved in starch metabolism; these are classified into several different families on the basis of their amino acid sequence similarities. Such binding domains promote attachment to the substrate and increase its concentration at the active site of the enzyme, which allows microorganisms to degrade non-soluble starch. Fold similarities are better conserved than sequences; nevertheless, it is possible to notice two evolutionary clusters of microbial starch-binding domains. These domains have enormous potential as tags for protein immobilization, as well as for the tailoring of enzymes that play a part in polysaccharide metabolism.
淀粉、纤维素和木聚糖等不同的不溶性多糖中的糖苷键分别被淀粉酶、纤维素酶和木聚糖酶水解。这些酶由微生物产生。它们具有模块化结构，由一个催化结构域和至少一个参与多糖结合的非催化结构域组成。淀粉结合模块存在于参与淀粉代谢的微生物酶中；根据其氨基酸序列相似性，这些模块被分为几个不同的家族。这种结合结构域促进与底物的附着，并增加其在酶活性位点的浓度，从而使微生物能够降解不溶性淀粉。折叠相似性比序列更保守；然而，可以注意到微生物淀粉结合结构域有两个进化簇。这些结构域作为蛋白质固定化的标签以及用于修饰参与多糖代谢的酶具有巨大潜力。
