Sialoglycopeptides obtained from a transplantable rat colorectal adenocarcinoma: a comparison with those from normal colonic mucosa.

A transplantable colorectal adenocarcinoma and the normal colonic mucosa derived from rats of ACI/N strain were digested successively with pronase, deoxyribonuclease, chondroitinase ABC, and heparitinase to obtain the corresponding glycopeptide fractions. The amino acid compositions of these two fractions suggested that the polypeptide backbones were quite similar. However, the electrostatic net charges of these fractions were shown to be different by cellulose acetate membrane electrophoresis, ion exchange chromatography, and measurement of sialic acid contents. The glycopeptide fraction derived from adenocarcinoma contained much greater quantities of less acidic glycopeptides than that derived from the normal colonic mucosa. The former exhibited much stronger blood group A and H activities than the latter. Moreover, the former reacted with Ricinus communis lectin I, whereas the latter did not react with this lectin. These results indicate that the carbohydrate structures of tumor sialoglycoproteins are different from those of the corresponding ones in the normal tissue from which the tumor has originated.