Acidα-Glucosidase from Human Gastrointestinal Mucosa–-Separation and Characterization

Abstract

The human small-intestinal mucosa contains, in addition to the brush border maltases with pH-optimum at about 6, a soluble, presumably lysosomal α-glucosidase with pH-optimum at 4–4.5. This enzyme was separated by gel filtration chromatography on Bio-Gel P–300 and characterized regarding iso-electric point, substrate specificity and effect of some inhibitors. Of the substrates tested maltose was hydrolysed most rapidly. p-Nitrophenyl α-glucoside and isomaltose were split as well. The enzyme had also glucoamylase activity. Turanose, but not sucrose, inhibited the enzyme. In the normal gastric mucosa the acid α-glucosidase is responsible for practically all the maltase activity, but in the jejunal mucosa only for a few per cent of it.