Studies on α-Glucosidase in Rice

Part I. Isolation and Some Properties of α-Glucosidase I and α-Glucosidase II

抄録

Two kinds of α-glucosidase which were homogeneous in disc electrophoretic and ultra-centrifugal analysis were isolated from rice seeds by means of ammonium sulfate fractionation and CM-cellulose, Sephadex G-100 and DEAE-cellulose column chromatography and desig-nated as α-glucosidase I and α-glucosidase II.
Both α-glucosidases hydrolyzed maltose and soluble starch to glucose and showed same optimal pH (4.0) on the both substrates. In addition, both enzymes acted on various c-linked gluco-oligosaccharides and soluble starch but little or not on α-linked hetero-glucosides and α-l, 6-glucan (dextran).
Activity of the enzymes on maltose and soluble starch was inhibited by Tris and erythritol. α-Glucosidase II was more sensitive to the inhibitors than α-glucosidase I.
Km value for maltose was 1.1 mm for α-glucosidase I and 2.0mM for α-glucosidase II.