The catabolism of low molecular weight-hydroxyethylated amylopectin in man. III. Further degradation of excreted polymer fragments.

Fragments of low molecular weight-hydroxyethylated amylopectin (LMW-HES) contained in the urine voided by a single normal man, 6 to 12 hours after receiving a dose of 56 g of this material, were either separated straightforwardly by gel filtration on a column of Sephadex G-200 or incubated for 18 hours at 37 degrees C in the presence of alpha-amylase contained in human saliva, and then subjected to filtration on the same column. Comparison of the two elution profiles revealed that LMW-HES material remaining in the bloodstream for 6-hours or more, had not been degraded by serum alpha-amylase to the maximum possible extent, since incubation with alpha-amylase in-vitro caused further catabolism. These data suggest that LMW-HES polymer fragments are excreted in the urine as soon as they obtain a molecular weight below the threshold of glomerular filtration.