Center for Agricultural Biomaterials, and Department of Food Science and Biotechnology, School of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Republic of Korea.
N Biotechnol. 2010 Sep 30;27(4):300-7. doi: 10.1016/j.nbt.2010.04.001. Epub 2010 Apr 10.
A gene encoding a hyperthermostable maltogenic amylase of Staphylothermus marinus (SMMA) was cloned and overexpressed in Escherichia coli. SMMA consisted of 696 amino acids with a predicted molecular mass of 82.5 kDa. The enzyme was active in acidic conditions (pH 3.5-5.0), with an optimal pH of 5.0, and was extremely thermostable, with a temperature optimum of 100 degrees C and a melting temperature of 109 degrees C, both of which extremely favored the starch conversion process. SMMA hydrolyzed linear malto-oligosaccharides, starch, cyclodextrins, and cycloamylose, primarily to maltose and glucose, and showed highest activity toward acarbose and pullulan, hydrolyzed to acarviosine-glucose and panose, respectively. Investigation of the cleavage mode using (14)C-maltoheptaose revealed that SMMA preferentially hydrolyzed the first and second glycosidic bonds from the reducing end. To our knowledge, this enzyme is the most thermostable maltogenic amylase yet reported, and might be of potential value in the food and starch industries.
一株嗜热海洋球菌（Staphylothermus marinus）来源的超高热稳定性麦芽糖淀粉酶（SMMA）的基因被克隆并在大肠杆菌中实现了过表达。SMMA 由 696 个氨基酸组成，预测分子量为 82.5 kDa。该酶在酸性条件下（pH 3.5-5.0）具有活性，最适 pH 为 5.0，且具有极高的热稳定性，最适温度为 100°C，熔点为 109°C，这两个特性都非常有利于淀粉转化过程。SMMA 可水解直链麦芽寡糖、淀粉、环糊精和环麦芽寡糖，主要产物为麦芽糖和葡萄糖，对阿卡波糖和普鲁兰的活性最高，分别水解为阿卡波糖-葡萄糖和潘糖。通过使用 (14)C-麦芽七糖进行的酶切模式研究表明，SMMA 优先从还原端水解第一和第二糖苷键。据我们所知，该酶是迄今为止报道的最耐热的麦芽糖淀粉酶，在食品和淀粉工业中可能具有潜在的应用价值。
