A Novel Cold-Active and Alkali-Stable β-Glucosidase Gene Isolated from the Marine Bacterium Martelella mediterranea
A Novel Cold-Active and Alkali-Stable β-Glucosidase Gene Isolated from the Marine Bacterium Martelella mediterranea
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DOI：
10.1007/s12010-010-8988-y
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发表时间：
2010-12-01
影响因子：
3
通讯作者：
Liu, Ziduo
中科院分区：
文献类型：
--
作者：
Mao, Xiaoxia;Hong, Yuzhi;Liu, Ziduo
通过构建地中海马尔泰氏菌2928的基因组文库，克隆了一个β-葡萄糖苷酶基因，命名为gluc 3 m。gluc 3 m由2，496 bp组成，编码832个氨基酸的肽，其与来自辐射农杆菌K84的家族3糖苷水解酶的β-葡萄糖苷酶具有最大的氨基酸相似性（59%）。Gluc 3 M的最适反应温度为45 ℃，最适pH为8.0。对硝基苯基-β-D-吡喃葡萄糖苷的Km和Vmax分别为0.18 mg/ml和196.08 μ mol/min/mg酶。发现Gluc 3 M具有高度的碱稳定性，在用pH 11.0缓冲液处理24 h后保留其最大酶活性的80%。此外，Gluc 3 M的活性在单价金属离子的存在下显著提高，而在二价离子的存在下被抑制。Gluc 3 M还对各种底物（包括pNPGlu、pNPGal、水杨苷和水杨酸粉末）表现出显著的活性。重要的是要注意，Gluc 3 M是一种冷活性酶，在4 ℃下显示出超过50%的最大酶活性。SWISS-MODEL分析表明，Gluc 3 M的低温活性与其保守结构域SDW附近的氨基酸有关。基于这些特性，Gluc 3 M具有用于其他研究和工业应用的潜力。
A beta-glucosidase gene designated gluc3m was cloned through construction of a genomic library of Martelella mediterranea 2928. The gluc3m consisted of 2,496 bp and encoded a peptide of 832 amino acids that shared the greatest amino acid similarity (59%) with a beta-glucosidase of family 3 glycoside hydrolase from Agrobacterium radiobacter K84. The optimum reaction temperature and pH of Gluc3M were 45 degrees C and 8.0, respectively. The K-m and V-max for p-nitrophenyl-beta-D-glucopyranoside were 0.18 mg/ml and 196.08 mu mol/min/mg enzyme, respectively. Gluc3M was found to be highly alkali stable, retaining 80% of its maximum enzymatic activity after treatment with pH 11.0 buffers for 24 h. Furthermore, the activity of Gluc3M improved remarkably in the presence of univalent metal ions, whereas it was inhibited in the presence of divalent ions. Gluc3M also exhibited significant activities toward various substrates including pNPGlu, pNPGal, salicin, and konjac powder. It is important to note that Gluc3M is a cold-active enzyme that showed over 50% of the maximum enzymatic activity at 4 degrees C. SWISS-MODEL revealed that the amino acids near the conserved domain SDW of Gluc3M contributed to the cold-active ability. Based on these characteristics, Gluc3M has the potential for use in additional studies and for industrial applications.