Department of Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University , Morioka, Iwate, Japan.
Department of Chemistry and Life Science, Kogakuin University , Hachioji, Tokyo, Japan.
Biosci Biotechnol Biochem. 2020 Dec;84(12):2499-2507. doi: 10.1080/09168451.2020.1805584. Epub 2020 Aug 16.
Di--acetylchitobiase (Ctbs) degrades β-1,4 glycoside bonds of the chitobiose core of free asparagine-linked glycan. This study examined whether Ctbs degrades chitin-oligosaccharides to GlcNAc in mammals. We analyzed Ctbs mRNA and protein expression in mouse tissues and characterized enzymatic activity using recombinant mouse Ctbs expressed in . Ctbs mRNA and protein were expressed in various tissues of mouse, including the stomach. Optimal conditions for recombinant Ctbs were pH 3.0 and 45°C, and the recombinant enzyme was retained more than 94% activity after incubation at pH 3.0-7.0 and below 37°C. The recombinant Ctbs hydrolyzed (GlcNAc) and (GlcNAc) at pH 3.0 and produced GlcNAc. The of Ctbs was lowest with (GlcNAc) as a substrate. / was fourfold as high with (GlcNAc) and (GlcNAc) as substrates than with (GlcNAc). These results suggest that Ctbs digests chitin-oligosaccharides or (GlcNAc) of reducing-end residues of oligosaccharides and produces GlcNAc in mouse tissues.
二乙酰壳二糖酶（Ctbs）降解游离天冬酰胺连接聚糖的壳二糖核心中的β-1,4 糖苷键。本研究探讨了 Ctbs 是否将壳寡糖降解为 GlcNAc。我们分析了 Ctbs mRNA 和蛋白在小鼠组织中的表达，并使用在 中表达的重组小鼠 Ctbs 来表征酶活性。Ctbs mRNA 和蛋白在包括胃在内的各种小鼠组织中表达。重组 Ctbs 的最佳条件为 pH3.0 和 45°C，在 pH3.0-7.0 和低于 37°C 孵育后，重组酶保留了超过 94%的活性。重组 Ctbs 在 pH3.0 下水解（GlcNAc）和（GlcNAc），并产生 GlcNAc。以（GlcNAc）作为底物时，Ctbs 的 最低。以（GlcNAc）和（GlcNAc）作为底物时， / 比以（GlcNAc）作为底物时高四倍。这些结果表明 Ctbs 在小鼠组织中消化壳寡糖或寡糖还原端残基的（GlcNAc），并产生 GlcNAc。
