Comparative Biochemical Studies of α-Glucosidases

Part I. Substrate Specificity and Transglucosidation Action of an α-Glucosidase of Brewer's Yeast

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The properties of brewer's yeast α-glucosidase have been investigated. The enzyme was capable of hydrolyzing various α-glucosides and was active especially on aryl-α-glucosides in comparison with other α-glucosides and sugars. The rate of hydrolysis decreased in following order: phenyl-α-glucosides, sucrose, matlose and isomaltose.
The range of opt. temp. was 40-45°C and opt. pH, 6.5-7.0.
Cu⁺⁺and Hg⁺⁺inhibited strongly the enzyme activity and Zn⁺⁺, moderately. The enzyme was suggested to be a sulfhydryl enzyme from the inhibition experiments by SH-reagents and the effects of glutathione on the activity.
The enzyme synthesized some oligosaccharides from maltose. As the transglucosidation products, nigerose, isomaltose, kojibiose and maltotriose were detected by paperchromatography.
Pure nigerosc was separated by splitting maltose with amyloglucosidase from the mixture of maltose and nigerose and by use of successive carbon column chromatography.