Li W, Dong Z, Cui F
Institute of Microbiology, The Chinese Academy of Sciences, Beijing 100080.
Wei Sheng Wu Xue Bao. 2000 Aug;40(4):420-4.
An extracellular neutral endo-beta-mannanase(endo-beta-1, 4-D-mannan mannanohydrolase, EC 3.2.1.78)of Bacillus subtilis BM9602 was purified to electrophoretic homogeneity by ammonium sulfate precipitation and DEAE-cellulose DE22 chromatography with 45.5 fold and 5.9% yield. It's molecular weight and pl value were 35 kD by SDS-PAGE and 4.5 by isoelectric focusing, respectively. The enzyme was the most active at pH 5.8. The optimum temperature of the enzyme activity was 50 degrees C. The enzyme was stable at pH 6.0-8.0 and below 50 degrees C. The activity of the enzyme was inhibited by Hg2+, Ag+ strongly. For various substrates, such as locust bean gum, guar gum, sesbania gum and konjac gum, Km and Vmax value of the enzyme were 3.8, 14.9, 11.3, 2.4 mg/mL, and 24.5, 86.5, 38.4, 19.8 mumol.min-1.mg-1, respectively. The enzyme hydrolize various plant beta-mannans, with valuable oligosaccharides and without monosaccharide.
通过硫酸铵沉淀和DEAE-纤维素DE22柱层析，对枯草芽孢杆菌BM9602分泌的一种胞外中性内切-β-甘露聚糖酶（内切-β-1,4-D-甘露聚糖甘露水解酶，EC 3.2.1.78）进行了纯化，纯化倍数为45.5倍，得率为5.9%，达到了电泳纯。经SDS-PAGE测定其分子量为35 kD，等电聚焦法测得其pI值为4.5。该酶在pH 5.8时活性最高，酶活性的最适温度为50℃。该酶在pH 6.0 - 8.0及50℃以下稳定。Hg2+、Ag+对该酶活性有强烈抑制作用。对于刺槐豆胶、瓜尔豆胶、田菁胶和魔芋胶等多种底物，该酶的Km值和Vmax值分别为3.8、14.9、11.3、2.4 mg/mL和24.5、86.5、38.4、19.8 μmol·min-1·mg-1。该酶能水解多种植物β-甘露聚糖，生成有价值的低聚糖且无单糖生成。
