Department of Bioengineering, Tatung University, 40 Chung-Shang North Road, 3rd Section, Taipei 104, Taiwan.
Molecules. 2012 Aug 14;17(8):9774-89. doi: 10.3390/molecules17089774.
Endoglucanase B (EGLB) derived from Aspergillus niger BCRC31494 has been used in the food fermentation industry because of its thermal and alkaline tolerance. It was cloned and expressed in Pichia pastoris. According to sequence analysis, the gene open reading frame comprises 1,217 bp with five introns (GenBank GQ292753). According to sequence and protein domain analyses, EGLB was assigned to glycosyl hydrolase family 5 of the cellulase superfamily. Several binding sites were found in the promoter region. The purified recombinant enzyme was induced by 0.5% methanol, and it exhibited optimal activity at 70 °C and pH 4. EGLB was stable for 3 h at temperatures below 60 °C, with more than 90% of its activity remaining. The enzyme was specific for substrates with β-1,3 and β-1,4 linkages. In Lineweaver-Burk plot analysis, the K(m) and V(max) values of EGLB for β-D-glucan were 134 mg/mL and 4.68 U/min/mg, respectively. The enzyme activity was increased by 1.86-fold by Co²⁺ and by 2-fold by Triton X-100 and Tween 80. These favorable properties make EGLB a potential candidate for use in laundry and textile industrial applications.
内切葡聚糖酶 B（EGLB）来源于黑曲霉 BCRC31494，因其具有耐热性和耐碱性而被应用于食品发酵工业。该酶已在毕赤酵母中被克隆和表达。根据序列分析，基因开放阅读框包含 1217bp，有 5 个内含子（GenBank GQ292753）。根据序列和蛋白结构域分析，EGLB 被分配到纤维素酶超家族的糖苷水解酶家族 5。在启动子区域发现了几个结合位点。纯化的重组酶在 0.5%甲醇的诱导下表达，最适反应温度为 70°C，最适 pH 值为 4。该酶在低于 60°C 的温度下稳定 3 小时，仍保持超过 90%的活性。该酶对具有β-1,3 和β-1,4 键的底物具有特异性。在 Lineweaver-Burk 作图分析中，EGLB 对β-D-葡聚糖的 K(m)和 V(max)值分别为 134mg/mL 和 4.68U/min/mg。Co²⁺使酶活性提高了 1.86 倍，Triton X-100 和 Tween 80 使酶活性提高了 2 倍。这些优良的性质使 EGLB 成为洗衣和纺织工业应用的潜在候选酶。
