| Abstract: | Two isoenzymes of amyloglucosidase, designated as AG-I and AG-II, elaborated exocellularly by a strain of Aspergillus niger van Tieghem, were separated and purified to homogeneity. The enzymes, produced in a selective medium, were separated and purified on a column of DEAE-Sephadex A-50. The molecular weights of AG-I and AG-II were found to be 69, 810 and 89,130 respectively. The two enzymes were glycoproteins and differed in their carbohydrate contents, pH and temperature stabilities and optima for activity. Their activation energies and Km values also varied. AG-II, had a higher molecular weight, carbohydrate content, increased acid tolerance and was synthesized earlier to AG-I (when the pH of the medium was acidic). Hg and Ag salts caused partial inhibition of their activities. |
