Abstract：
A novel glycoside hydrolase (GH) family 16 multi-domain β-1,3-1,4-glucanase (FsGlc16A) from Fibrobacter sp. UWP2 was identified, heterogeneously expressed, and its enzymatic properties, protein structure and application potential were characterized. Enzymological characterization showed that FsGlc16A performed the optimal catalytic activity at pH 4.5 and 50 °C with a specific activity of 3263 U/mg. FsGlc16A exhibited the substrate specificity towards oat β-glucan, barley β-glucan and lichenan, and in addition, it hydrolyzed oat β-glucan and lichenan into different β-glucooligosaccharides with polymerization degrees of 3-4, which further illustrated that it belonged to the endo-type β-1,3-1,4-glucanase. FsGlc16A was classified in subfamily25 of GH16. A \'PXSSSS\' repeats domain was identified at the C-terminus of FsGlc16A, which was distinct from the typical GH family 16 β-1,3-1,4-glucanases. Removing the \'PXSSSS\' repeats domain affected the binding of the substrate to FsGlc16A and reduced the enzyme activity. FsGlc16A displayed good potential for the applications, which hydrolyzed oat bran into β-glucooligosaccharides, and reduced filtration time (18.89 %) and viscosity (3.64 %) in the saccharification process. This study investigated the enzymatic properties and domain function of FsGlc16A, providing new ideas and insights into the study of β-1,3-1,4-glucanase.
摘要：
一种来自纤维杆菌的新型糖苷水解酶（GH）家族16多域β-1,3-1,4-葡聚糖酶（FsGlc16A）。UWP2被确定，异质表达，和它的酶学特性，蛋白质结构和应用潜力进行了表征。酶学表征表明，FsGlc16A在pH4.5和50°C下表现出最佳的催化活性，比活性为3263U/mg。FsGlc16A表现出对燕麦β-葡聚糖的底物特异性，大麦β-葡聚糖和地衣，此外,它将燕麦β-葡聚糖和地衣聚糖水解成聚合度为3-4的不同β-葡萄糖寡糖，进一步说明它属于内型β-1,3-1,4-葡聚糖酶。FsGlc16A被归类为GH16的亚家族25。在FsGlc16A的C端鉴定出一个\'PXSSSS\'重复结构域,它不同于典型的GH家族16β-1,3-1,4-葡聚糖酶。去除'PXSSSS'重复结构域会影响底物与FsGlc16A的结合并降低酶活性。FsGlc16A显示出良好的应用潜力，将燕麦麸皮水解成β-葡萄糖寡糖，并减少糖化过程中的过滤时间(18.89%)和粘度(3.64%)。本研究调查了FsGlc16A的酶学性质和结构域功能，为β-1,3-1,4-葡聚糖酶的研究提供新的思路和见解。
