- 學位論文
Orpinomyces sp. Cel6葡聚醣水解酶之結構與功能分析
Structural and functional analysis of the Eukaryotic Orpinomyces sp. glucanase Cel6
摘要
內切型葡聚醣水解酶(EC 3.2.1.91)屬於糖苷鍵水解酶家族6，能裂解纖維素的β-1,4-糖苷鍵，並釋放纖維寡糖為主要產物。本實驗使用的葡聚醣水解酶(OsCel6)是從Orpinomyces sp. PC-2所篩選出來的，含有一錨定區域(dockerin domain, residues 1-100)和一催化區域(OsCel6, residues 105-449)。OsCel6的晶體結構解析度為1.8 A，並顯示此酵素含有一個開放式的裂縫。OsCel6的開放式裂縫與Thermobifida fusca Cel6A 和 Humicola insolens Cel6B的內切型葡聚醣水解酶相似。結構分析猜測位於活性區域的兩段loop (loop1; residues 201-218, and loop2; residues 410-425) 能夠向催化區域的方向擺動，導致形成活性隧道而具有外切活性。酵素活性分析顯示催化區域的主要活性為內切型活性。
並列摘要
Endoglucanases (EC 3.2.1.91) that belong to GH 6 glycosyl hydrolase, cleave the ?β-1,4-glucosidic linkage of cellulose and release cellooliogsaccharides as the major product. Endoglucanase from Orpinomyces sp. PC-2 contains two subunits of dockerin domain (residues 1-100) and catalytic domain (OsCel6, residues 105-449). The crystal structure of OsCel6 at a resolution of 1.8 A, reveals this enzyme contains an open cleft active site. The topology of OsCel6 open cleft active site is similar to those of Thermobifida fusca Cel6A and Humicola insolens Cel6B endoglucanase. The structural study suggests that two loops (loop1; residues 201-218, and loop2; residues 410-425) located around the active site is likely to move to form a tunnel active site for exo-activity. Enzymatic function data reveal that OsCel6 functions as a major endoglucanase activity.