Small intestinal sucrase and isomaltase split the bond between glucosyl-C1 and the glycosyl oxygen.
The products of the hydrolysis of sucrose and palatinose by the sucrase-isomaltase complex from rabbit small intestine were investigated by persilylation followed by gas-liquid chromatography and mass spectrometry. If the hydrolysis is carried out in H218O, the heavy oxygen is found exclusively at the Ci of the alpha-glucopyranose formed. The 18O enrichment equals that of the incubation medium. The oxygen exchange between the monosaccharides and water is not accelerated by the sucrase-isomaltase complex. These observations show that the bond split by the sucarse and the isomaltase moiety of the complex is the one between glucosyl-Ci and the glucosyl oxygen. They agree with the mechanism proposed for these carbohydrases in the accompanying paper (Cogoli, A., and Semenza, G. (1975) J. Biol. Chem. 250, 7802-7809) involving the formation of an oxocarbonium ion.
D000818:Animals; D006026:Glycoside Hydrolases / Q000378:metabolism*; D007421:Intestine, Small / Q000201:enzymology*; D013058:Mass Spectrometry; D009097:Multienzyme Complexes / Q000378:metabolism; D009844:Oligosaccharides; D010103:Oxygen Isotopes; D011817:Rabbits; D013393:Sucrase / Q000378:metabolism*
D009097:Multienzyme Complexes; D009844:Oligosaccharides; D010103:Oxygen Isotopes; D006026:Glycoside Hydrolases; D013393:Sucrase