The use of equilibrium density-gradient ultracentrifugation in the isolation and characterisation of glycoproteins with blood group P1 activity from sheep hydatid-cyst fluid.

Equilibrium density-gradient ultracentrifugation in caesium choride and caesium sulphate has been used in the isolation and fractionation of the glycoproteins specific for blood-group P1 from hydatid cyst fluids. The fractions obtained have distinct and systematic differences specifically related to their buoyant densities, chemical compositions and specific-activities for group P1. High levels of specific-activity were maintained over a large range of chemical compositions. The peptide content varied systematically from 2.5% for the densest fraction to 37% for the least dense fraction. The amino acid composition was essentially constant over all fractions. The proportion of glucosamine decreased and the proportions of galactosamine, mannose and glucose increased with increasing peptide content of the fractions. The data presented suggest the present of oligosaccharide side-chains of various lengths and compositions and/or the presence of oligosaccharide side-chains with very different chemical compositions, of which only some are associated with the specificity for group P1. The properties of the glycoproteins from hydatid cyst fluids have been compared with those of the glycoproteins from human ovarian cysts. Although some similarities have been demonstrated there are significant differences.