Demonstration of sucrase-isomaltase complex in chick intestine.

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Abstract
Sucrase and isomaltase form an enzyme-enzyme complex in chick intestine. Some of the properties of the disaccharidases were compared with those of other species. Chick intestinal sucrase and isomaltase existed in the form of an enzyme-enzyme complex, shown from the results of polyacrylamide disc gel electrophoresis, DEAE Sephadex A-25 ion exchange column chromatography and citraconylation, although the chick intestinal sucrase and isomaltase were not retained on a Sephadex G-200 column. The MW of the sucrase-isomaltase complex, maltase I, maltase II, maltase III and isomaltase, dissociated from the sucrase-isomaltase complex, were 250,000, 250,000, 160,000, 225,000 and 80,000, respectively, obtained from polyacrylamide disc gel electrophoresis. The optimum pH for all the enzymes was 6.0. Km values of sucrase, isomaltase, maltase I and maltase III were 10.0, 3.5, 1.0 and 4.6 mM, respectively, Vmax values for sucrase, isomaltase, maltase I and maltase III were 217.4, 281.4, 147.1 and 454.5 .mu.mol substrate hydrolyzed/mg protein per h, respectively.