Isolation and Characterization of a Glycopeptide from Mucinous Carcinoma of Human Stomach

Glycopeptides from mucinous carcinoma of human stomach as well as normal and pathological stomach tissues without mucinous degeneration were extracted by protein digestion with papain [EC 3. 4. 4. 10] and trypsin [EC 3. 4. 4. 4]. Electrophoresis in barbital buffer, pH 8.6, on cellulose acetate strips revealed that mucinous carcinoma possessed alcianophilic and PAS stainable components which migrated toward the anode slower than hyaluronic acid, although normal tissues and other pathological tissues without mucinous degeneration contained none or scarcely any. This component was isolated by Pevikon block electrophoresis. It possessed sialic acid, fucose, galactose, glucosamine and galactosamine as major carbohydrate components. Its basophilic character was shown to be due to its relatively high sialic acid content and low content of ester sulfate groups. Thus it belonged to the group of sialomucins in epithelial mucus. In its carbohydrate composition, except for the high fucose content, and also the abundance of threonine in the peptide moiety it was quite similar to the pseudomucin of ovarian cyst adenocarcinoma. The physical characters of the two, such as their optical rotation, viscosity and sedimentation coefficients, were also very similar.