Huang L, Hseu T H, Wey T T
Institute of Life Science, National Tsing Hua University, Hsinchu, Taiwan.
Biochem J. 1991 Sep 1;278 ( Pt 2)(Pt 2):329-33. doi: 10.1042/bj2780329.
Trichoderma koningii G-39 produced xylanases in submerged culture using oat spelt xylan or crystalline cellulose, Avicel, as the sole carbon source. A low-Mr xylanase was purified from the culture filtrate by ion-exchange chromatography on SP-Trisacryl-M and gel filtration on Fractogel TSK HW-50F. It was homogeneous on SDS/PAGE and isoelectric focusing. A typical procedure provided about 11-fold purification with 4.5% protein yield and 50% activity recovery. The purified enzyme has an Mr value of about 21,500 and a pI of 8.9. Its specific activity was 6100 units/mg of protein, with optimal activity towards 0.5% xylan at about pH 5.5 and 60 degrees C. The purified enzyme had no activity against CM-cellulose with a degree of substitution of 0.63. It also showed no beta-xylosidase activity. The Km and Vmax. values, as determined with the soluble fraction of oat spelt xylan as substrate, were 0.70 mg/ml and 1.85 x 10(6) mumol/min per mg of enzyme respectively. Hg2+ (1 mM) and SDS (10 mM) completely inhibited xylanase activity, whereas Ca2+ showed no significant effect on the enzyme activity at 1 mM, but gave 80% inhibition at 10 mM. The enzyme contained about 4.4% carbohydrate and showed an immunological relationship to a cellobiohydrolase from the same fungal strain.
康宁木霉G-39在以燕麦麸木聚糖或微晶纤维素（Avicel）作为唯一碳源的深层培养中产生木聚糖酶。通过在SP-Trisacryl-M上进行离子交换色谱以及在Fractogel TSK HW-50F上进行凝胶过滤，从培养滤液中纯化出一种低分子量木聚糖酶。它在SDS/PAGE和等电聚焦上均一。一个典型的步骤可提供约11倍的纯化，蛋白质产率为4.5%，活性回收率为50%。纯化后的酶的Mr值约为21,500，pI为8.9。其比活性为6100单位/毫克蛋白质，在约pH 5.5和60℃时对0.5%木聚糖具有最佳活性。纯化后的酶对取代度为0.63的CM-纤维素没有活性。它也没有β-木糖苷酶活性。以燕麦麸木聚糖的可溶部分为底物测定的Km和Vmax值分别为0.70毫克/毫升和每毫克酶1.85×10(6)微摩尔/分钟。1毫摩尔的Hg2+和10毫摩尔的SDS完全抑制木聚糖酶活性，而1毫摩尔的Ca2+对酶活性没有显著影响，但在10毫摩尔时产生80%的抑制。该酶含有约4.4%的碳水化合物，并与同一真菌菌株的纤维二糖水解酶存在免疫关系。
