Structural Aspects of Heterologous Blood‐Group‐P₁ Substance

Blood‐group‐P 1 substance from sheep hydatid‐cyst fluid was purified by a combination of gel filtration through Sepharose 6B and preparative polyacrylamide‐gel electrophoresis. The resultant glycoprotein contained D‐galactose; D‐glucose; N ‐acetyl‐D‐glucosamine and N ‐acetyl‐D‐galactosamine in molar ratios 5.2:1:2:2; unidentified carbohydrate was also present. The amino‐acid composition resembled that of vertebrate A, B, H and Lewis active glycoproteins. Prolonged incubation of P 1 substance with coffee bean α‐galactosidase resulted in the liberation of 17–24% of the total D‐galactose present and a reduction in blood‐group‐P 1 inhibitory activity. The serological activity of the glycoprotein was unaffected by treatment with pronase or papain. P 1 substance has receptors for the agglutinins from Salmo trutta, Clupea harengus, Soja hispida, Maclura aurantiaca and Triticum vulgaris. Some loss of receptor for Soja hispida and Maclura aurantiaca occurred after α‐D‐galactosidase treatment.