Enhancement of Catalytic Activity of Chemically Modified Subtilisin Carlsberg in Benzene by Adjustment of Lyophilization Conditions
作者:Oh Hyeong Kwon、Yukio Imanishi、Yoshihiro Ito
DOI:10.1246/bcsj.73.1277
日期:2000.5
Alteration of the lyophilization conditions significantly enhanced not only the activity of insoluble native subtilisin Carlsberg but also that of solubilized enzyme in benzene. The catalytic activity (kcat/Km) for the transesterification reaction of N-acetyl-L-phenylalanine ethyl ester with 1-propanol in benzene was enhanced more than 1000 times by the solubilization (100-fold enhancement) and the adjustment of lyophilization conditions (10-fold enhancement). Subtilisin Carlsberg was modified with polyethylene glycol (PEG-Sub) so that it could be solubilized in organic solvents. The effects of pH of the aqueous enzyme solution, of salts, or of a substrate analog in the aqueous solution before the lyophilization process, on the catalytic activity of native subtilisin and PEG-Sub were investigated. The activities of both the native subtilisin and PEG-Sub depended on the pH. The activities of both PEG-Sub and the native subtilisin were enhanced by the presence of salts. The presence of a substrate analog, N-Ac-L-Phe, also enhanced the activity of the native subtilisin and PEG-Sub. These results demonstrated that the organic solvent-solubilized subtilisin was affected by the lyophilization conditions.
冻干条件的改变不仅显著提高了不溶性天然枯草杆菌蛋白酶的活性,还提高了苯中可溶性酶的活性。通过可溶化(提高100倍)和调整冻干条件(提高10倍),N-乙酰-L-苯丙氨酸乙酯与苯中1-丙醇的酯交换反应的催化活性(kcat/Km)提高了1000倍以上。用聚乙二醇(PEG-Sub)对枯草杆菌蛋白酶进行了修饰,使其能够在有机溶剂中溶解。研究了冻干前水溶液中酶溶液的pH值、盐或底物类似物对天然枯草杆菌蛋白酶和PEG-Sub催化活性的影响。天然枯草杆菌蛋白酶和PEG-Sub的活性都取决于pH值。盐的存在提高了PEG-Sub和天然枯草杆菌蛋白酶的活性。底物类似物N-Ac-L-Phe的存在也提高了天然枯草杆菌蛋白酶和PEG-Sub的活性。这些结果表明,有机溶剂可溶化的枯草杆菌蛋白酶受冻干条件的影响。