Department of Parasitology, School of Basic Medical Science, Central South University, Changsha, 410013, Hunan, China.
Department of Microbiology, School of Basic Medical Science, Central South University, Changsha, 410013, Hunan, China.
Sci Rep. 2023 Apr 10;13(1):5840. doi: 10.1038/s41598-023-32161-y.
Glycoside hydrolases (GHs), the enzymes that break glycosidic bonds, are ubiquitous in the ecosystem, where they perform a range of biological functions. As an interesting glycosidase family, Glycoside hydrolase family 97 (GH97) contains α-glucosidase, α-galactosidase, and glucoamylase. Only ten members of GH97 have been characterized so far. It is critical to explore novel members to elucidate the catalytic mechanism and application potential of GH97 family. In this study, a novel glucoamylase QsGH97a from Qipengyuania seohaensis SW-135 was cloned and expressed in E. coli. Sequence analysis and NMR results show that QsGH97a is classified into GH97a, and adopts inverting mechanism. The biochemical characterization indicates that QsGH97a shows the optimal activity at 50 °C and pH 8.0. Ca has little effect on the catalytic activity; however, the activity can be substantially increased by 8-13 folds in the presence of Ba or Sr. Additionally, the metal content of QsGH97a assay showed a high proportion of Sr. The specific metal activity was initially revealed in glucoamylases, which is not found in other members. These results imply that QsGH97a not only is a new member of GH97, but also has potential for industrial applications. Our study reveals that Ba or Sr may be involved in the catalytic mechanism of glucoamylase, laying the groundwork for a more complete knowledge of GH97 and its possible industrial application.
糖苷水解酶（GHs）是断裂糖苷键的酶，广泛存在于生态系统中，在那里它们执行各种生物功能。作为一个有趣的糖苷酶家族，糖苷水解酶家族 97（GH97）包含α-葡萄糖苷酶、α-半乳糖苷酶和糖化酶。迄今为止，只有 10 个 GH97 成员得到了表征。探索新成员对于阐明 GH97 家族的催化机制和应用潜力至关重要。在这项研究中，从 Qipengyuania seohaensis SW-135 中克隆并在大肠杆菌中表达了一种新型糖化酶 QsGH97a。序列分析和 NMR 结果表明，QsGH97a 被分类为 GH97a，采用反转机制。生化特性表明，QsGH97a 在 50°C 和 pH8.0 下表现出最佳活性。Ca 对催化活性影响不大；然而，在存在 Ba 或 Sr 的情况下，活性可以增加 8-13 倍。此外，QsGH97a 测定的金属含量显示出 Sr 的高比例。在糖化酶中首次发现了特定的金属活性，而在其他成员中则没有发现。这些结果表明，QsGH97a 不仅是 GH97 的一个新成员，而且具有工业应用的潜力。我们的研究表明，Ba 或 Sr 可能参与了糖化酶的催化机制，为更完整地了解 GH97 及其可能的工业应用奠定了基础。
