Three Forms of α-Glucosidase and a Glucoamylase fromAspergillus awamori

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Abstract
Aspergillus awamori produced multiple forms (isoenzymes) of α-glucosidase, three of which could be separated from one another by DEAE-cellulose column chromatography, and a glucoamylase. The α-glucosidases isolated were designated as α-glucosidase I, α-glucosidase II and α-glucosidase III. They were homogeneous on gel electrofocusing and ultracentrifugation, respectively. The glucoamylase preparation was homogeneous on disc gel electrophoresis, gel electrofocusing and ultracentrifugation. The molecular weight of α-glucosidase I, α-glucosidase II, and α-glucosidase III, and glucoamylase was 125,000, 140,000, 130,000 and 88,000 to 83,700, respectively. The three α-glucosidases hydrolyzed maltose, maltotriose, phenyl α-maltoside, isomaltose, panose, phenyl α-glucoside, and amylose liberating glucose, but did not act on sucrose. Glucoamylase hydrolyzed maltose, maltotriose, phenyl α-maltoside, soluble starch, amylose, amylopectin, and glycogen, and glucose was the sole product formed in the digests of these substrates. They hydrolyzed phenyl α-maltoside into glucose and phenyl α-glucoside. Glucoamylase hydrolyzed rice starch, amylose, amylopectin, and glycogen, converting them almost completely into glucose. It was found that β-glucose was liberated from amylose by the action of glucoamylase. Isomaltose and panose were the main α-glucosyltransfer products formed from maltose by the three α-glucosidases. Certain properties of these enzymes also were investigated in the present work.

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