Gastrointestinal Digestion of Starch

In terminal starch digestion in the small intestine, the enzymes oligo-1 ,6glucosidase and maltase (a-glucosidase) have been shown to complete the hydrolysis of the saccharides left after cr-amylase action (1).In a previous paper, oligo-1,6-glucosidase has been identified, partially separated from maltase, and differentiated from the polysaccharide debranching enzyme amylo-l ,6-glucosidase (1).In this paper some of the properties of the intestinal carbohydrases are presented.Particular attention has been paid to the possible importance of histidine in enzymatic hydrolysis.Some of this work has been the subject of a preliminary report (2).The properties of amylo-l ,6-glucosidase are reported in another communication (3). Materials and MethodsEnzymes-Oligo-l , 6-glucosidase was prepared essentially as previously described (1).It has been found that higher yields are obtained when the enzyme is fractionated in the presence of Versene.Accordingly, 0.001 M Versene was included in all aqueous solvents used.Solid ammonium sulfate was used during the fractionation in place of a saturated solution.Solid KHCOs was used to adjust the pH to 7 after ammonium sulfate addition.Unless otherwise stated, fractions in these experiments were 18 to 44 per cent ethanol fractions.The preparation of maltase essentially free of oligo-1 ,Bglucosidase activity is described in a later section.Other enzymes were prepared by methods already cited (1). Coenzymes and Substrates and InhibitorsThe sources or methods of preparation of coenzymes and substrates have been listed (1).Tris(hydroxymethyl)aminomethane (Tris), purchased from the Sigma Chemical Company, was sublimed before use.tert-Butylamine, 2-amino-2-methyl-1-propanol, and 2-amino-2-methyl-1,3-propanediol were purchased from the Eastman Kodak Company.