The recently identified lytic polysaccharide monooxygenases (LPMOs) are important auxiliary proteins which contribute to lignocellulose biodegradation by oxidatively cleaving the glycosidic bonds in cellulose and other polysaccharides. The vast differences in terms of substrate specificity and regioselectivity within LPMOs provide us new possibilities to find promising candidates for the use in enzyme cocktails in biorefinery applications. In this study, a highly xyloglucan active family AA9 lytic polysaccharide monooxygenase EpLPMO9A was identified from Eupenicillium parvum 4-14. EpLPMO9A exhibited a mixed C1/C4 oxidative cleavage activity on cellulose and xyloglucan with a broad range of pH stability and good thermal stability at 40 °C. It showed a higher boosting effect on the enzymatic saccharification of complex lignocellulosic substrates associated with xyloglucan than on the lignocellulosic substrates without xyloglucan particularly in low commercial cellulase dosage cases. The oxidative cleavage of xyloglucan by EpLPMO9A may facilitate to open up the sterical hindrance of cellulose by xyloglucan and thereby increase accessibility for cellulase to lignocellulosic substrates. The discovery of more and more hemicellulose-active LPMOs and their contribution to breaking down the barriers by oxidatively acting on hemicellulose may expand our knowledge for their functions of LPMOs in lignocellulose biodegradation.

最近鉴定的裂解多糖单加氧酶（LPMO）是重要的辅助蛋白，通过氧化裂解纤维素和其他多糖中的糖苷键，有助于木质纤维素的生物降解。LPMO中底物特异性和区域选择性方面的巨大差异为我们提供了新的可能性，以寻找有希望的候选物用于生物精炼应用中的酶混合物。在这项研究中，从小青霉（Eupenicillium parvum） 4-14中鉴定了一种高木葡聚糖活性家族AA9裂解多糖单加氧酶Ep LPMO9A 。EPLPMO9A在纤维素和木葡聚糖上具有混合的C1 / C4氧化裂解活性，在40°C下具有宽范围的pH稳定性和良好的热稳定性。与没有木葡聚糖的木质纤维素底物相比，它对与木葡聚糖相关的复杂木质纤维素底物的酶促糖化表现出更高的促进作用，特别是在低商业纤维素酶剂量的情况下。Ep对木葡聚糖的氧化裂解LPMO9A可以促进木葡聚糖打开纤维素的空间位阻，从而增加纤维素酶对木质纤维素底物的可及性。越来越多的具有半纤维素活性的LPMO的发现及其通过氧化作用于半纤维素而打破壁垒的贡献，可能会扩大我们对LPMO在木质纤维素生物降解中的功能的认识。