Molecular Enzymology Group, University of Groningen, The Netherlands.
FEBS Lett. 2020 Sep;594(17):2819-2828. doi: 10.1002/1873-3468.13854. Epub 2020 Jun 18.
Chitooligosaccharide oxidase (ChitO) is a fungal carbohydrate oxidase containing a bicovalently bound FAD cofactor. The enzyme is known to catalyse the oxidation of chitooligosaccharides, oligomers of N-acetylated glucosamines derived from chitin degradation. In this study, the unique substrate acceptance was explored by testing a range of N-acetyl-d-glucosamine derivatives, revealing that ChitO preferentially accepts carbohydrates with a hydrophobic group attached to C2. The enzyme also accepts streptozotocin, a natural product used to treat tumours. Elucidation of the crystal structure provides an explanation for the high affinity towards C2-decorated glucosamines: the active site has a secondary binding pocket that accommodates groups attached at C2. Docking simulations are fully in line with the observed substrate preference. This work expands the knowledge on this versatile enzyme.
壳寡糖氧化酶（ChitO）是一种真菌糖氧还蛋白，含有双共价结合的黄素腺嘌呤二核苷酸辅因子。该酶已知能催化壳寡糖的氧化，壳寡糖是壳聚糖降解产生的 N-乙酰氨基葡萄糖的低聚物。在这项研究中，通过测试一系列 N-乙酰-d-葡萄糖胺衍生物，探索了其独特的底物接受能力，结果表明 ChitO 优先接受在 C2 上连接有疏水性基团的碳水化合物。该酶还能接受链脲佐菌素，这是一种用于治疗肿瘤的天然产物。晶体结构的阐明为其对 C2 修饰的葡萄糖胺的高亲和力提供了一个解释：活性位点有一个容纳 C2 上连接基团的二级结合口袋。对接模拟完全符合观察到的底物偏好。这项工作扩展了对这种多功能酶的认识。
