1. The content and distribution of
carbohydrate was examined in mucus glycopolypeptides from human
antral mucosae. 2. The mean amount of
carbohydrate per 1000
amino acid residues was found to be similar in glycopolypeptides with A, B or H activity. It was slightly, though significantly, less in glycopolypeptides lacking these determinants, because
carbohydrate chains were of a shorter average length than in the A-, B- or H-active preparations. This difference was reflected in the sizes of
oligosaccharide-
alcohols released from representative glycopolypeptides with alkaline
borohydride. 3. Differences between A-, B- or H-active and non-secretor glycopolypeptides in terms of the mean number of
carbohydrate chains per 1000
amino acid residues were found to be small, and without significance. 4. The average number of peripheral
monosaccharide units per 1000
amino acid residues was greater in A-active than in H-active, and least in non-secretor, glycopolypeptides. This order was reversed for
monosaccharide units incorporated into skeletal (core plus backbone) structures. The difference in each case was statistically significant. 5. These findings suggest that the increased risk of
peptic ulcer associated with
blood group O and non-secretor status is unlikely to be attributable to an inherent deficiency in the protective mucus layer, linked to differences between
mucins that are associated with A, B or H activity. Other hypotheses linked to
infection with Helicobacter pylori are examined.