Purification and some properties of glucoamylase from Aspergillus niger H-9
1985
Phenporn Pongpuncharoen
Aspergillus niger H-9 is a fungal strain isolated from rotting cassava tuber in Thailand. In the present study, the production of the enzymes was produced on solid ricebran-soybean cultivation. Two types of glycoamylases were isolated and purified. The purified glyucoamylasses were found to be homogenous on 7.5% polyacrylamide gel disc electrophoresis. The molecular weights of glucoamylase I and II were 66,000 and 47,800 respectively. The Km values of glucoamylase I and glycoamylase II were 12.5 and 6.25 mg glucose/ml when soluble starch was used as a substrate. Both enzymes were stable at pH range between 3.0-6.0 and temperature stability were below 50 deg. C. The optimal pH of both enxymes were at 4.0-5.0. The optimum temperature for the activity of glucoamylase I and glucoamylase II were 60 deg. C. and 75 deg. C. respectively. Both glucoamylases I and II were active on various kinds of starch and dextrin including raw starch. However, glucoamylase II was found to hydrolyze raw starch better than glucoamylase I
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