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Alpha-glucosidase (, ''maltase'', ''glucoinvertase'', ''glucosidosucrase'', ''maltase-glucoamylase'', ''alpha-glucopyranosidase'', ''glucosidoinvertase'', ''alpha-D-glucosidase'', ''alpha-glucoside hydrolase'', ''alpha-1,4-glucosidase'', ''alpha-D-glucoside glucohydrolase'') is a glucosidase located in the brush border of the small intestine that acts upon 1,4-alpha bonds.〔 This is in contrast to beta-glucosidase. Alpha-glucosidase breaks down starch and disaccharides to glucose. Maltase, a similar enzyme that cleaves maltose, is nearly functionally equivalent. Other glucosidases include: * Cellulase * Beta-glucosidase * Debranching enzyme ==Mechanism== Alpha-glucosidase hydrolyzes terminal non-reducing 1-4 linked alpha- glucose residues to release a single alpha- glucose molecule.〔 Alpha-glucosidase is a carbohydrate-hydrolase that releases alpha-glucose as opposed to beta-glucose. Beta-glucose residues can be released by glucoamylase, a functionally similar enzyme. The substrate selectivity of alpha-glucosidase is due to subsite affinities of the enzyme’s active site.〔 Two proposed mechanisms include a nucleophilic displacement and an oxocarbenium ion intermediate.〔 *Rhodnius prolixus, a blood-sucking insect, forms hemozoin (Hz) during digestion of host hemoglobin. Hemozoin synthesis is dependent on the substrate binding site of alpha-glucosidase.〔 *Trout liver alpha-glucosidases were extracted and characterized. It was shown that for one of the trout liver alpha-glucosidases maximum activity of the enzyme was increased by 80% during exercise in comparison to a resting trout. This change was shown to correlate to an activity increase for liver glycogen phosphorylase. It is proposed that alpha-glucosidase in the glucosidic path plays an important part in complementing the phosphorolytic pathway in the liver’s metabolic response to energy demands of exercise.〔 *Yeast and rat small intestinal alpha-glucosidases have been shown to be inhibited by several groups of flavonoids.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Alpha-glucosidase」の詳細全文を読む スポンサード リンク
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