贵州大学酿酒与食品工程学院,国家林业和草原局刺梨工程技术研究中心,贵州省农畜产品贮藏加工重点实验室,贵阳 550025
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国家自然科学基金(31860446),贵州省科学技术基金(黔科合基础[2019]1104)和贵州省科技计划(黔科合平台人才[2018]5781号)资助项目.
School of Liquor & Food Engineering, Guizhou University, National Forestry and Grassland Bureau Prickly Pear Engineering Technology Research Center, Key Laboratory of Agricultural and Animal Products Store and Processing of Guizhou Province, Guiyang 550025, China
This work was supported by grants from The National Natural Science Foundation of China (31860446), Guizhou Provincial Science and Technology Fund (Qiankehe Foundation [2019] 1104) and Guizhou Provincial Science and Technology Project (Qiankehe Platform Talent [2018]5781).
嗜酸乳杆菌(Lactobacillus acidophilus)是益生菌,前期研究发现Lactobacillus acidophilus GIM1.208所产生的β-葡萄糖苷酶(BGL)具有较高活性,为探明其结构与特性,本研究采用PCR体外扩增技术获得Lactobacillus acidophilus GIM1.208 BGL的目的基因,并在大肠杆菌中成功表达,经镍亲和层析等蛋白质纯化技术获得纯度达90%以上的蛋白质样品,进而通过圆二色光谱法(CD)和同源建模法对BGL的二级结构和三级结构进行测定分析并研究其酶学性质. 结果表明,Lactobacillus acidophilus BGL的分子质量为52 ku,纯化后浓度为1.88 g/L,二级结构包括15.9% α螺旋、44.1% β折叠、18.1% β转角、27.2%无规则卷曲,其三维结构显示,该蛋白质有8个β折叠和8个α螺旋,整体呈圆锥形. Lactobacillus acidophilus BGL具有良好的葡萄糖耐受性与NaCl耐受性,最适反应温度为47℃,最适反应pH为5.6,在20℃~50℃范围内和pH2.2~6.0间有较高的稳定性,且乙酸乙酯、甲醇对酶活性抑制作用明显,Fe3+、Fe2+对酶有显著激活作用. 上述研究结果为Lactobacillus acidophilus BGL后续功能发掘和应用研究提供了重要参考依据.
Lactobacillus acidophilus is a kind of probiotics. The previous research found that β-glucosidase (BGL) produced by Lactobacillus acidophilus GIM1.208 has high activity. In order to elucidate its structure and characteristics, the target gene of Lactobacillus acidophilus GIM1.208 BGL was obtained with PCR and successfully expressed in E. coli. Protein samples with a purity of more than 90% was obtained by nickel affinity chromatography. Then the secondary structure of BGL was detected by circular dichroism spectroscopy (CD) and its tertiary structure was analyzed by homology modeling method. The enzymatic properties of Lactobacillus acidophilus BGL was also studied. The results show that the molecular mass of Lactobacillus acidophilus BGL is 52 ku, the concentration after purification is 1.88 g/L. The secondary structure of Lactobacillus acidophilus BGL includes 15.9% α-helix, 44.1% β-sheet, 18.1% β-turn, and 27.2% random coil. Homology modeling analyzation showed that 8 β-sheets and 8 α-helices were included in 3D structure of Lactobacillus acidophilus BGL, and the whole protein is conical in shape. Lactobacillus acidophilus BGL has good glucose tolerance and NaCl tolerance. The optimal temperature and the optimal pH of this enzyme is 47℃ and 5.6, respectively. Lactobacillus acidophilus BGL has high stability in the range of 20℃-50℃ and pH 2.2-6.0. The inhibitory effect of ethyl acetate and methanol on enzyme activity is obvious, and Fe3+ and Fe2+ have significant activation effect on enzyme. These results provide important reference basis for the subsequent functional exploration and application research of Lactobacillus acidophilus BGL.
余奕宏,丁小娟,丁筑红,宋煜婷,王翼.嗜酸乳杆菌GIM1.208 β-葡萄糖苷酶的异源表达、纯化及酶学性质研究[J].生物化学与生物物理进展,2021,48(1):88-99
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