Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China.
Int J Mol Sci. 2022 May 9;23(9):5276. doi: 10.3390/ijms23095276.
Xyloglucan is closely associated with cellulose and still retained with some modification in pretreated lignocellulose; however, its influence on lignocellulose biodegradation is less understood. GH74 from s displayed much higher catalytic activity than previously characterized fungal GH74 xyloglucanases. The carbohydrate-binding module 1 (CBM1) deleted variant (GH74ΔCBM) had the same optimum temperature and pH but an elevated thermostability. GH74 displayed a high binding affinity on xyloglucan and cellulose, while GH74ΔCBM completely lost the adsorption capability on cellulose. Their hydrolysis action alone or in combination with other glycoside hydrolases on the free xyloglucan, xyloglucan-coated phosphoric acid-swollen cellulose or pretreated corn bran and apple pomace was compared. CBM1 might not be essential for the hydrolysis of free xyloglucan but still effective for the associated xyloglucan to an extent. GH74 alone or synergistically acting with the CBH1/EG1 mixture was more effective in the hydrolysis of xyloglucan in corn bran, while GH74ΔCBM showed relatively higher catalytic activity on apple pomace, indicating that the role and significance of CBM1 are substrate-specific. The degrees of synergy for GH74 or GH74ΔCBM with the CBH1/EG1 mixture reached 1.22-2.02. The addition of GH10 xylanase in GH74 or the GH74ΔCBM/CBH1/EG1 mixture further improved the overall hydrolysis efficiency, and the degrees of synergy were up to 1.50-2.16.
木葡聚糖与纤维素密切相关，在预处理的木质纤维素中仍有一些修饰保留；然而，其对木质纤维素生物降解的影响了解较少。来自 s 的 GH74 表现出比以前表征的真菌 GH74 木葡聚糖酶更高的催化活性。缺失碳水化合物结合模块 1 (CBM1) 的变体 (GH74ΔCBM) 具有相同的最适温度和 pH，但热稳定性更高。GH74 对木葡聚糖和纤维素表现出高结合亲和力，而 GH74ΔCBM 完全失去了对纤维素的吸附能力。单独或与其他糖苷水解酶组合，对游离木葡聚糖、木葡聚糖涂层磷酸化膨胀纤维素或预处理玉米麸皮和苹果渣进行水解作用的比较。CBM1 对于游离木葡聚糖的水解可能不是必需的，但在一定程度上仍然对相关木葡聚糖有效。GH74 单独或与 CBH1/EG1 混合物协同作用在玉米麸皮中水解木葡聚糖的效果更好，而 GH74ΔCBM 在苹果渣中表现出相对较高的催化活性，表明 CBM1 的作用和意义是特定于底物的。GH74 或 GH74ΔCBM 与 CBH1/EG1 混合物的协同度达到 1.22-2.02。在 GH74 或 GH74ΔCBM/CBH1/EG1 混合物中添加 GH10 木聚糖酶进一步提高了整体水解效率，协同度达到 1.50-2.16。
