Division of Biochemical Sciences, National Chemical Laboratory, Pune, India.
Extremophiles. 2012 Jan;16(1):135-46. doi: 10.1007/s00792-011-0413-0. Epub 2011 Nov 26.
Xyloglucanase from an extracellular culture filtrate of alkalothermophilic Thermomonospora sp. was purified to homogeneity with a molecular weight of 144 kDa as determined by SDS-PAGE and exhibited specificity towards xyloglucan with apparent K (m) of 1.67 mg/ml. The enzyme was active at a broad range of pH (5-8) and temperatures (40-80°C). The optimum pH and temperature were 7 and 70°C, respectively. The enzyme retained 100% activity at 50°C for 60 h with half-lives of 14 h, 6 h and 7 min at 60, 70 and 80°C, respectively. The kinetics of thermal denaturation revealed that the inactivation at 80°C is due to unfolding of the enzyme as evidenced by the distinct red shift in the wavelength maximum of the fluorescence profile. Xyloglucanase activity was positively modulated in the presence of Zn(2+), K(+), cysteine, β-mercaptoethanol and polyols. Thermostability was enhanced in the presence of additives (polyols and glycine) at 80°C. A hydrolysis of 55% for galactoxyloglucan (GXG) from tamarind kernel powder (TKP) was obtained in 12 h at 60°C and 6 h at 70°C using thermostable xyloglucanases, favouring a reduction in process time and enzyme dosage. The enzyme was stable in the presence of commercial detergents (Ariel), indicating its potential as an additive to laundry detergents.
来自嗜碱耐热菌（Thermomonospora sp.）胞外培养滤液的木聚糖酶经 SDS-PAGE 纯化至均一性，分子量为 144 kDa，对木聚糖具有特异性，表观 K m 为 1.67 mg/ml。该酶在较宽的 pH（5-8）和温度（40-80°C）范围内具有活性。最适 pH 和温度分别为 7 和 70°C。该酶在 50°C 下保持 100%活性 60 h，半衰期分别为 14 h、6 h 和 7 min 在 60、70 和 80°C。热变性动力学表明，80°C 下的失活是由于酶的展开，这可以从荧光谱波长最大值的明显红移得到证明。木聚糖酶活性在 Zn(2+)、K(+)、半胱氨酸、β-巯基乙醇和多元醇的存在下得到正向调节。在 80°C 时，添加剂（多元醇和甘氨酸）存在时可提高热稳定性。在 60°C 下 12 小时和 70°C 下 6 小时，使用耐热木聚糖酶可使来自罗望子仁粉（TKP）的半乳糖木聚糖（GXG）水解 55%，有利于缩短处理时间和减少酶用量。该酶在商业洗涤剂（Ariel）存在下稳定，表明其有望作为洗衣洗涤剂的添加剂。
