Purification and characterization of a pig intestinal alpha-limit dextrinase.
Mucosa from the duodenal and jejunal regions of pig small intestine was repeatedly freeze-thaw treated to solubilize an enzyme preparation, enriched in maltase, glucoamylase and alpha-limit dextrinase activities; isomaltase and sucrase remained essentially insoluble during the treatment. Chromatographic procedures, including ion-exchange, gel filtration and hydroxylapatite chromatography of the solubilized preparation, brought to homogeneity an alpha-glucosidase active towards maltose, alpha-limit dextrins and starch in decreasing order, with only a very weak capacity to hydrolyse alpha-1,6-linkages. Michaelis constants and maximal velocities, as well as relative rates of hydrolysis of several substrates, including maltodextrins and alpha-limit dextrins, were determined and served to characterize what seems to be a rather specific alpha-1,4-glucosidase. The participation of this enzyme in the hydrolysis of alpha-limit dextrins and more generally in pathways for starch breakdown in the pig digestive tract is examined and discussed.
D000818:Animals; D002499:Centrifugation, Density Gradient; D002845:Chromatography; D004591:Electrophoresis, Polyacrylamide Gel; D005959:Glucosidases / Q000302:isolation & purification*; D007413:Intestinal Mucosa / Q000201:enzymology; D007421:Intestine, Small / Q000201:enzymology; D007700:Kinetics; D008970:Molecular Weight; D013379:Substrate Specificity; D013552:Swine; D000520:alpha-Glucosidases / Q000032:analysis / Q000302:isolation & purification*
D005959:Glucosidases; D000520:alpha-Glucosidases