Tajana E, Fiechter A, Zimmermann W
Institute of Biotechnology, ETH-Hönggerberg, Zürich, Switzerland.
Appl Environ Microbiol. 1992 May;58(5):1447-50. doi: 10.1128/aem.58.5.1447-1450.1992.
A nonsporulating strain of Streptomyces diastaticus producing alpha-L-arabinofuranosidase activity (EC 3.2-1.55) was isolated from soil. Two alpha-L-arabinosidases were purified by ion-exchange chromatography and chromatofocusing. The enzymes had molecular weights of 38,000 (C1) and 60,000 (C2) and pIs of 8.8 and 8.3, respectively. The optimum pH range of activity for both enzymes was between 4 and 7. The apparent Km values with p-nitrophenyl arabinofuranoside as the substrate were 10 mM (C1) and 12.5 mM (C2). C1 retained 50% of its activity after 8 h of incubation at 25 degrees C, while C2 retained 80% activity. After 3 h of incubation at 50 degrees C, C1 lost 90% of its initial activity while C2 lost only 40%. The purified enzymes hydrolyzed p-nitrophenyl alpha-L-arabinofuranoside and liberated arabinose from arabinoxylan and from a debranched beta-1,5-arabinan.
从土壤中分离出一株不产孢的淀粉酶链霉菌，该菌株具有α-L-阿拉伯呋喃糖苷酶活性（EC 3.2-1.55）。通过离子交换色谱和色谱聚焦法纯化了两种α-L-阿拉伯糖苷酶。这两种酶的分子量分别为38,000（C1）和60,000（C2），等电点分别为8.8和8.3。两种酶的最适pH活性范围均在4至7之间。以对硝基苯基阿拉伯呋喃糖苷为底物时，其表观Km值分别为10 mM（C1）和12.5 mM（C2）。C1在25℃孵育8小时后保留了50%的活性，而C2保留了80%的活性。在50℃孵育3小时后，C1失去了90%的初始活性，而C2仅失去了40%。纯化后的酶可水解对硝基苯基α-L-阿拉伯呋喃糖苷，并从阿拉伯木聚糖和去分支的β-1,5-阿拉伯聚糖中释放出阿拉伯糖。
