Tavobilov I M, Rodionova N A, Bezborodov A M
Prikl Biokhim Mikrobiol. 1983 Mar-Apr;19(2):232-9.
Properties of exo-1,4-beta-xylosidase from the fungus Aspergillus niger 15 were investigated. The enzyme was homogeneous during gel filtration, electrophoresis in polyacrylamide gel in the presence and absence of Na dodecyl sulfate, ultracentrifugation and isoelectric focusing. The enzyme had a temperature optimum at 70 degrees, pH optimum 3.8-4.0 for p-nitrophenyl-beta-D-xylopyranoside (p-NPX), was stable at pH 3-8, retained its 100% activity for 1 hour at 50 degrees and 42% activity at 60 degrees. Km was 0.23 mM for p-NPX and 0.67 mM for xylobiose. Xylose was a competitive inhibitor of exo-1,4-beta-xylodidase with Ki = 2.9 mM. The enzyme showed a transglycosilase activity. The aminoacid analysis of exo-1,4-beta-xylosidase showed that the enzyme molecule contained predominantly dicarboxylic and hydrophobic amino acids as well as serine. The enzyme contained no carbohydrates. Its activity was inhibited by p-chloromercury benzoate.
对黑曲霉15的外切 - 1,4 - β - 木糖苷酶的性质进行了研究。该酶在凝胶过滤、在有无十二烷基硫酸钠存在下的聚丙烯酰胺凝胶电泳、超速离心和等电聚焦过程中均表现为均一。该酶对对硝基苯基 - β - D - 木吡喃糖苷（p - NPX）的最适温度为70℃，最适pH为3.8 - 4.0，在pH 3 - 8时稳定，在50℃下1小时保留其100%的活性，在60℃下保留42%的活性。对p - NPX的Km为0.23 mM，对木二糖的Km为0.67 mM。木糖是外切 - 1,4 - β - 木糖苷酶的竞争性抑制剂，Ki = 2.9 mM。该酶表现出转糖苷酶活性。外切 - 1,4 - β - 木糖苷酶的氨基酸分析表明，该酶分子主要含有二羧酸和疏水氨基酸以及丝氨酸。该酶不含碳水化合物。其活性受到对氯汞苯甲酸的抑制。
