Shofiqur Rahman A K, Kawamura S, Hatsu M, Hoq M M, Takamizawa K
Department of Bioprocessing, Faculty of Agriculture, Gifu University, Yanagido, Japan.
Can J Microbiol. 2001 Aug;47(8):767-72. doi: 10.1139/w01-064.
The zygomycete fungus Rhizomucor pusillus HHT-1, cultured on L(+)arabinose as a sole carbon source, produced extracellular alpha-L-arabinofuranosidase. The enzyme was purified by (NH4)2SO4 fractionation, gel filtration, and ion exchange chromatography. The molecular mass of this monomeric enzyme was 88 kDa. The native enzyme had a pI of 4.2 and displayed a pH optimum and stability of 4.0 and 7.0-10.0, respectively. The temperature optimum was 65 degrees C, and it was stable up to 70 degrees C. The Km and Vmax for p-nitrophenyl alpha-L-arabinofuranoside were 0.59 mM and 387 micromol x min(-1) x mg(-1) protein, respectively. Activity was not stimulated by metal cofactors. The N-terminal amino acid sequence did not show any similarity to other arabinofuranosidases. Higher hydrolytic activity was recorded with pnitrophenyl alpha-L-arabinofuranoside, arabinotriose, and sugar beet arabinan; lower hydrolytic activity was recorded with oat-spelt xylan and arabinogalactan, indicating specificity for the low molecular mass L(+)-arabinose containing oligosaccharides with furanoside configuration.
在以L(+)阿拉伯糖作为唯一碳源培养的情况下，接合菌纲真菌米根霉HHT-1产生了胞外α-L-阿拉伯呋喃糖苷酶。该酶通过硫酸铵分级沉淀、凝胶过滤和离子交换色谱法进行纯化。这种单体酶的分子量为88 kDa。天然酶的pI为4.2，其最适pH值和稳定性分别为4.0以及7.0 - 10.0。最适温度为65℃，在70℃时仍保持稳定。对硝基苯基α-L-阿拉伯呋喃糖苷的Km和Vmax分别为0.59 mM和387 μmol·min⁻¹·mg⁻¹蛋白质。金属辅因子不会刺激其活性。N端氨基酸序列与其他阿拉伯呋喃糖苷酶没有任何相似性。对硝基苯基α-L-阿拉伯呋喃糖苷、阿拉伯三糖和甜菜阿拉伯聚糖的水解活性较高；对燕麦-斯佩尔特木聚糖和阿拉伯半乳聚糖的水解活性较低，表明该酶对具有呋喃糖苷构型的低分子量含L(+)-阿拉伯糖的寡糖具有特异性。
