Abstract
The hydrolytic activity of the rat small intestine with respect to the newly developed sugar substitute palatinose condensates was characterized using brush border membranes and purified sucraseisomaltase and glucoamylase. Palatinose dimer, palatinose trimer and palatinose tetramer were all hydrolyzed yielding glucose at rates similar to that of palatinose by small intestinal brush border membranes. The kinetic constant, Km and Vmax values of sucrase-isomaltase complex in the case of the palatinose condensates were similar to those for palatinose. Purified glucoamylase also hydrolyzed the palatinose dimer, trimer and tetramer, but the Km values for these palatinose condensates were approximately 10 times greater than in the case of palatinose, suggesting that at low concentrations the contribution of glucoamylase to the hydrolysis of palatinose condensates is small. These results suggest that small intestinal isomaltase possesses broad substrate specificity for palatinose condensates regardless of the number of condensed palatinose molecules and that palatinose condensates are readily hydrolyzed by sucrase-isomaltase to produce glucose and residual fructose condensates.
