Ogawa K, Uejima O, Nakakuki T, Usui T, Kainuma K
Research Laboratory, Nihon Shokuhin Kako Co., Ltd., Shizuoka, Japan.
Agric Biol Chem. 1990 Mar;54(3):581-6.
An extracellular maltohexaose-forming amylase [EC 3.2.1.98] from Klebsiella pneumoniae mutant is a normal hydrolytic enzyme that hydrolyzes short-chain amylose (DP = 23) to give about 40% maltohexaose. Transglycosylation from maltoheptaose to the 4-position of p-nitrophenyl alpha-glucoside was efficiently induced through the use of maltohexaose-forming amylase in an aqueous methanol solution. The enzyme specifically produced p-nitrophenyl alpha-maltoheptaoside (13% of the p-nitrophenyl alpha-glucoside) from maltoheptaose as a donor and p-nitrophenyl alpha-glucoside as an acceptor. The yield of p-nitrophenyl alpha-maltoheptaoside depended on the concentration of methanol solvent, the pH, and temperature. Furthermore, the use of the aqueous methanol system in the reaction not only improved the solubility of p-nitrophenyl alpha-glucoside but also greatly increased the formation of p-nitrophenyl alpha-maltoheptaoside, which is a useful substrate for assay of human amylase in serum and urine.
肺炎克雷伯菌突变体产生的一种胞外形成麦芽六糖的淀粉酶[EC 3.2.1.98]是一种正常的水解酶，它能水解短链直链淀粉（聚合度=23），产生约40%的麦芽六糖。在甲醇水溶液中，通过使用形成麦芽六糖的淀粉酶，可有效诱导从麦芽七糖到对硝基苯基α-葡萄糖苷4位的转糖基化反应。该酶以麦芽七糖作为供体、对硝基苯基α-葡萄糖苷作为受体，特异性地产生对硝基苯基α-麦芽七糖苷（占对硝基苯基α-葡萄糖苷的13%）。对硝基苯基α-麦芽七糖苷的产率取决于甲醇溶剂的浓度、pH值和温度。此外，反应中使用甲醇水溶液体系不仅提高了对硝基苯基α-葡萄糖苷的溶解度，还大大增加了对硝基苯基α-麦芽七糖苷的形成，而对硝基苯基α-麦芽七糖苷是血清和尿液中人类淀粉酶检测的有用底物。
