Purification and Characterization of a Pig Intestinal α‐Limit Dextrinase

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Abstract
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 α‐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 α‐glucosidase active towards maltose, α‐limit dextrins and starch in decreasing order, with only a very weak capacity to hydrolyse α‐1,6‐linkages. Michaelis constants and maximal velocities, as well as relative rates of hydrolysis of several substrates, including maltodextrins and α‐limit dextrins, were determined and served to characterize what seems to be a rather specific α‐1,4‐glucosidase. The participation of this enzyme in the hydrolysis of α‐limit dextrins and more generally in pathways for starch breakdown in the pig digestive tract is examined and discussed.