Department of Pharmacology, School of Basic Medicine, Qingdao University, Qingdao 266071, China.
Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China.
Mar Drugs. 2019 Oct 23;17(11):599. doi: 10.3390/md17110599.
As an important medical enzyme, β-galactosidases catalyze transgalactosylation to form prebiotic Galacto-Oligosaccharides (GOS) that assist in improving the effect of intestinal flora on human health. In this study, a new glycoside hydrolase family 2 (GH2) β-galactosidase-encoding gene, galA, was cloned from the Antarctic bacterium Alteromonas sp. ANT48 and expressed in The recombinant β-galactosidase GalA was optimal at pH 7.0 and stable at pH 6.6-7.0, which are conditions suitable for the dairy environment. Meanwhile, GalA showed most activity at 50 °C and retained more than 80% of its initial activity below 40 °C, which makes this enzyme stable in normal conditions. Molecular docking with lactose suggested that GalA could efficiently recognize and catalyze lactose substrates. Furthermore, GalA efficiently catalyzed lactose degradation and transgalactosylation of GOS in milk. A total of 90.6% of the lactose in milk could be hydrolyzed within 15 min at 40 °C, and the GOS yield reached 30.9%. These properties make GalA a good candidate for further applications.
作为一种重要的医学酶，β-半乳糖苷酶通过转半乳糖基作用催化形成有助于改善肠道菌群对人体健康的益生元半乳糖低聚糖（GOS）。在这项研究中，从南极细菌 Alteromonas sp.ANT48 中克隆了一种新的糖苷水解酶家族 2（GH2）β-半乳糖苷酶编码基因 galA，并在 中表达。重组β-半乳糖苷酶 GalA 的最适 pH 值为 7.0，在 pH6.6-7.0 时稳定，这是适合乳品环境的条件。同时，GalA 在 50°C 时表现出最高的活性，在 40°C 以下保留超过 80%的初始活性，这使得该酶在正常条件下稳定。与乳糖的分子对接表明，GalA 可以有效地识别和催化乳糖底物。此外，GalA 可以有效地催化牛奶中乳糖的降解和 GOS 的转半乳糖基作用。在 40°C 下，15 分钟内可水解牛奶中 90.6%的乳糖，GOS 的产率达到 30.9%。这些特性使 GalA 成为进一步应用的良好候选者。
