Composition of mucoid fractions from duodenal fluid of children and of adults

Abstract 1. 1. About 90% of nondialyzable carbohydrate of the duodenal fluid is present in the form of TCA-soluble mucoids containing 70–75 % carbohydrate with the composition of a fucomucopolysaccharide. 2. 2. A small fraction of the TCA-soluble carbohydrate obtained by ethanol and acetone fractionation consisted of a fucomucopolysaccharide with less than 5% protein. 3. 3. The TCA-soluble mucoid represents a mixture of two different types of mucoids distinguished by differences in their solubilities in ethanol and the nature of their mucopolysaccharides. 4. 4. One type of mucoid is present in fractions which precipitate at 67% ethanol. The hexose in its mucopolysaccharide consists of more than 80% of galactose and only traces of mannose, the hexosamine of comparable amounts of glucosamine and galactosamine. 5. 5. The second type does not precipitate below 90% ethanol. The hexose in its mucopolysaccharide consists of comparable amounts of galactose and mannose and the hexosamine predominantly of glucosamine. 6. 6. In both types of mucoids from fluids of children, the molar ratio of fucose to hexosamine is very nearly 1:2. In mucoids from fluids of adults this ratio is 1.2:2. 7. 7. Subfractionation of the two types of mucoids with ethanol yields subfractions, the polysaccharides of which differ in their content in sialic acid. 8. 8. The ratios of hexosamine and galactose to sialic acid in the ethanol subfractions run parallel to their solubility in ethanol. 9. 9. The comparison of the composition of the total mucoid soluble in 67% ethanol with that of its ethanol and acetone subfractions yields suggestive evidence of an asymmetry of the mucoid molecule based on variations in the distribution of its sugar constituents along the chain of its mucopolysaccharide.