Department of Biotechnology, KRIBB School of Bioscience, Korea University of Science and Technology (UST), Daejeon 34113, Korea.
Industrial Bio-Materials Research Center, KRIBB, Daejeon 34141, Korea.
Biomolecules. 2021 Nov 21;11(11):1735. doi: 10.3390/biom11111735.
Endo-type chitinase is the principal enzyme involved in the breakdown of -acetyl-d-glucosamine-based oligomeric and polymeric materials through hydrolysis. The gene (966-bp) encoding a novel endo-type chitinase (ChiJ), which is comprised of an N-terminal chitin-binding domain type 3 and a C-terminal catalytic glycoside hydrolase family 19 domain, was identified from a fibrolytic intestinal symbiont of the earthworm , HY-13. The highest endochitinase activity of the recombinant enzyme (rChiJ: 30.0 kDa) toward colloidal shrimp shell chitin was found at pH 5.5 and 55 °C and was considerably stable in a wide pH range (3.5-11.0). The enzyme exhibited the highest biocatalytic activity (338.8 U/mg) toward ethylene glycol chitin, preferentially degrading chitin polymers in the following order: ethylene glycol chitin > colloidal shrimp shell chitin > colloidal crab shell chitin. The enzymatic hydrolysis of -acetyl-β-d-chitooligosaccharides with a degree of polymerization from two to six and colloidal shrimp shell chitin yielded primarily -diacetyl-β-d-chitobiose together with a small amount of -acetyl-d-glucosamine. The high chitin-degrading ability of inverting rChiJ with broad pH stability suggests that it can be exploited as a suitable biocatalyst for the preparation of -diacetyl-β-d-chitobiose, which has been shown to alleviate metabolic dysfunction associated with type 2 diabetes.
内切型几丁质酶是参与通过水解分解基于 N-乙酰基-d-葡萄糖的低聚和多聚材料的主要酶。从蚯蚓的纤维分解肠道共生体 HY-13 中鉴定出一种新型内切型几丁质酶（ChiJ）的基因（966bp），该基因由 N 端几丁质结合域类型 3 和 C 端催化糖苷水解酶家族 19 域组成。重组酶（rChiJ：30.0 kDa）对胶体虾壳几丁质的最高内切几丁质酶活性在 pH5.5 和 55°C 下发现，在较宽的 pH 范围内（3.5-11.0）相当稳定。该酶对乙二醇几丁质表现出最高的生物催化活性（338.8 U/mg），优先降解几丁质聚合物，以下降序排列：乙二醇几丁质>胶体虾壳几丁质>胶体蟹壳几丁质。具有聚合度从二到六的 N-乙酰基-β-d-壳二糖和胶体虾壳几丁质的 -乙酰-β-d-壳寡糖的酶促水解主要产生 -二乙酰基-β-d-壳二糖，同时少量产生 -乙酰基-d-葡萄糖胺。rChiJ 具有反转和广泛的 pH 稳定性的高几丁质降解能力表明，它可以用作制备 -二乙酰基-β-d-壳二糖的合适生物催化剂，已经表明 -二乙酰基-β-d-壳二糖可以缓解与 2 型糖尿病相关的代谢功能障碍。
