Boyer E W, Ingle M B
J Bacteriol. 1972 Jun;110(3):992-1000. doi: 10.1128/jb.110.3.992-1000.1972.
A selective medium was used to isolate a bacterium (Bacillus species NRRL B-3881) that produced extracellular alkaline amylase in an alkaline medium (pH 9.5). Maximal enzyme yield was obtained in an aerated medium after 21 hr at 36 C. The enzyme was purified 18-fold by ultrafiltration and ammonium sulfate precipitation. Three active isoenzymes (one major and two minor) of alkaline amylase were detected by disc electrophoresis in polyacrylamide gel. The enzyme was only 12% inactivated by 20 mm ethylenediaminetetraacetic acid after 1 hr at pH 9.2 and 32 C. The optimal temperature was 50 C at pH 9.2, and the optimal pH was 9.2 at 50 C. The enzyme was stable between pH 7.5 and 10. It had an endomechanism of substrate encounter. The products produced from amylose and amylopectin had the beta-configuration. Cyclomaltoheptaose was hydrolyzed to maltotriose, maltose, and glucose. The main final product produced from amylose and amylopectin was beta-maltose; the other final products were maltotriose and small quantities of glucose and maltotetraose. The predominant product at early stages of hydrolysis was maltotetraose; other products were maltose through maltonanaose.
使用一种选择性培养基分离出一种细菌（芽孢杆菌属NRRL B - 3881），该细菌在碱性培养基（pH 9.5）中产生细胞外碱性淀粉酶。在36℃的通气培养基中培养21小时后可获得最大酶产量。通过超滤和硫酸铵沉淀将该酶纯化了18倍。通过聚丙烯酰胺凝胶圆盘电泳检测到碱性淀粉酶的三种活性同工酶（一种主要的和两种次要的）。在pH 9.2和32℃下处理1小时后，该酶仅被20 mM乙二胺四乙酸灭活12%。在pH 9.2时，最佳温度为50℃；在50℃时，最佳pH为9.2。该酶在pH 7.5至10之间稳定。它具有底物遭遇的内膜机制。直链淀粉和支链淀粉产生的产物具有β构型。环麦芽七糖被水解为麦芽三糖、麦芽糖和葡萄糖。直链淀粉和支链淀粉产生的主要最终产物是β - 麦芽糖；其他最终产物是麦芽三糖以及少量的葡萄糖和麦芽四糖。水解早期的主要产物是麦芽四糖；其他产物是从麦芽糖到麦芽九糖。
