Hong Mi-Ri, Park Chang-Su, Oh Deok-Kun
Department of Bioscience and Biotechnology, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, South Korea.
Biotechnol Lett. 2009 Sep;31(9):1439-43. doi: 10.1007/s10529-009-0019-0. Epub 2009 May 21.
A recombinant putative glycoside hydrolase from Caldicellulosiruptor saccharolyticus was purified with a specific activity of 12 U mg(-1) by heat treatment and His-Trap affinity chromatography, and identified as a single 56 kDa band upon SDS-PAGE. The native enzyme is a dimer with a molecular mass of 112 kDa as determined by gel filtration. The enzyme exhibited its highest activity when debranched arabinan (1,5-alpha-L-arabinan) was used as the substrate, demonstrating that the enzyme was an endo-1,5-alpha-L-arabinanase. The K (m), k (cat), and k (cat)/K (m) values were 18 mg ml(-1), 50 s(-1), and a 2.8 mg ml(-1) s(-1), respectively. Maximum enzyme activity was at pH 6.5 and 75 degrees C. The half-lives of the enzyme at 65, 70 and 75 degrees C were 2440, 254 and 93 h, respectively, indicating that it is the most thermostable of the known endo-1,5-alpha-L-arabinanases.
通过热处理和His-Trap亲和层析法纯化了来自嗜热解纤维梭菌的一种重组假定糖苷水解酶，其比活性为12 U mg(-1)，在SDS-PAGE上鉴定为一条单一的56 kDa条带。通过凝胶过滤测定，天然酶是一种分子量为112 kDa的二聚体。当使用去分支阿拉伯聚糖（1,5-α-L-阿拉伯聚糖）作为底物时，该酶表现出最高活性，表明该酶是一种内切-1,5-α-L-阿拉伯聚糖酶。K(m)、k(cat)和k(cat)/K(m)值分别为18 mg ml(-1)、50 s(-1)和2.8 mg ml(-1) s(-1)。最大酶活性在pH 6.5和75℃时出现。该酶在65、70和75℃下的半衰期分别为2440、254和93小时，表明它是已知内切-1,5-α-L-阿拉伯聚糖酶中最耐热的。
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