来自极端嗜热厌氧细菌Tok6-B1的一种细胞相关的寡聚-1,6-α-葡萄糖苷酶。
A cell-associated oligo-1,6-alpha-glucosidase from an extremely thermophilic anaerobic bacterium, Thermoanaerobium Tok6-B1.
作者信息
Plant A R, Parratt S, Daniel R M, Morgan H W
机构信息
Department of Biological Sciences, University of Waikato, Hamilton, New Zealand.
出版信息
Biochem J. 1988 Nov 1;255(3):865-8. doi: 10.1042/bj2550865.
Cell-associated oligo-1,6-alpha-glucosidase (EC 3.2.1.10) was isolated from Thermoanaerobium Tok6-B1 grown on starch-containing medium. Activity was purified 11.4-fold by salt precipitation, gel filtration, hydroxyapatite and anion-exchange chromatography. Molecular mass was determined as 30,000 by SDS/polyacrylamide-gel electrophoresis and 33,000 by analytical gel filtration. The probable order of specificity was p-nitrophenyl-alpha D-glucose greater than-isomaltose greater than-isomaltotriose greater than-panose greater than-nigerose and no activity was shown against malto-oligosaccharides, melezitose, melibiose, raffinose, cellobiose, sophorose, gentiobiose, lactose, pullulan, dextran or amylose. The optima for activity and stability were between pH 5.6 and 7.0 and the half-life at pH 6.5 was 1000 min at 70 degrees C and 20 min at 76 degrees C. Activity was stabilized by substrate, Mg2+, Mn2+ and Ca2+, but was destabilized by Zn2+ and EDTA. N-Ethylmaleimide, glucose and 1-O-methyl-alpha D-glucose were inhibitory but 1-O-methyl-beta D-glucose stimulated activity. The activation energy (Ea) was 109 kJ/mol.
从在含淀粉培养基上生长的嗜热厌氧菌Tok6-B1中分离出细胞相关的寡聚-1,6-α-葡萄糖苷酶（EC 3.2.1.10）。通过盐沉淀、凝胶过滤、羟基磷灰石和阴离子交换色谱法将活性纯化了11.4倍。通过SDS/聚丙烯酰胺凝胶电泳测定分子量为30,000，通过分析凝胶过滤测定为33,000。特异性的可能顺序为对硝基苯基-α-D-葡萄糖＞异麦芽糖＞异麦芽三糖＞潘糖＞黑曲霉糖，对麦芽寡糖、松三糖、蜜二糖、棉子糖、纤维二糖、槐糖、龙胆二糖、乳糖、支链淀粉、葡聚糖或直链淀粉无活性。活性和稳定性的最适pH在5.6至7.0之间，在pH 6.5时，70℃下的半衰期为1000分钟，76℃下为20分钟。底物、Mg2+、Mn2+和Ca2+可稳定活性，但Zn2+和EDTA会使其失稳。N-乙基马来酰亚胺、葡萄糖和1-O-甲基-α-D-葡萄糖具有抑制作用，但1-O-甲基-β-D-葡萄糖可刺激活性。活化能（Ea）为109 kJ/mol。
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