Kamran Aysha, Bibi Zainab, Aman Afsheen, Ul Qader Shah Ali
1Georg-August University School of Science (GAUSS), Georg-August-University Goettingen, Göttingen, Germany.
2Department of Biotechnology, University of Karachi, Karachi, 75270 Pakistan.
J Food Sci Technol. 2019 Jan;56(1):167-176. doi: 10.1007/s13197-018-3470-x. Epub 2018 Nov 13.
The β-galactosidase is an industrially valuable enzyme and used to hydrolyze the lactose into glucose and galactose. Considering the broad utility profile in food industry, β-galactosidase from was purified and characterized in term of its catalytic properties and stability. It displayed highest catalytic efficiency at 60 °C after 10.0 min within acidic pH environment (pH 5). The β-galactosidase exhibited 100% and 60% catalytic activity at 40 °C and 50 °C, respectively even after 120.0 min. The β-galactosidase activity was remained stable in the presence of Zn, Ni, and Mg ions. The activity was also retained in all investigated organic solvents except DMSO at various ionic concentrations. The surfactants Triton X-100 and SDS caused positive impact on the catalytic activity of enzyme at 1.0 mM concentration. However, the percent relative activity of β-galactosidase was significantly reduced when incubated with EDTA. The molecular mass of β-galactosidase estimated to be 95 kDa. The SEM micrographs of ONPG before and after β-galactosidase treatment indicated a remarkable difference in the morphology and proved the strong catalytic strength of enzyme. The β-galactosidase also demonstrated exceptional storage stability at - 80 °C, - 20 °C and 4 °C by retaining 86, 79 and 70% activity even after 100.0 days.
β-半乳糖苷酶是一种具有工业价值的酶，用于将乳糖水解为葡萄糖和半乳糖。鉴于其在食品工业中的广泛用途，对来自[具体来源未给出]的β-半乳糖苷酶进行了纯化，并对其催化特性和稳定性进行了表征。在酸性pH环境（pH 5）中，10.0分钟后，它在60°C时表现出最高的催化效率。即使在120.0分钟后，β-半乳糖苷酶在40°C和50°C时分别表现出100%和60%的催化活性。β-半乳糖苷酶在锌、镍和镁离子存在下活性保持稳定。在各种离子浓度下，除二甲基亚砜（DMSO）外，在所有研究的有机溶剂中该酶活性也得以保留。表面活性剂吐温X-100和十二烷基硫酸钠（SDS）在1.0 mM浓度时对酶的催化活性有积极影响。然而，与乙二胺四乙酸（EDTA）孵育时，β-半乳糖苷酶的相对活性百分比显著降低。β-半乳糖苷酶的分子量估计为95 kDa。β-半乳糖苷酶处理前后邻硝基苯-β-D-半乳糖苷（ONPG）的扫描电子显微镜（SEM）图像显示出形态上的显著差异，证明了该酶具有很强的催化能力。β-半乳糖苷酶在-80°C、-20°C和4°C下也表现出出色的储存稳定性，即使在100.0天后仍分别保留86%、79%和70%的活性。
