Blood-group-P, 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-ghcosamhe 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, substance with coffee bean ol-galactosidase resulted in the liberation of 17-240/, of the total D-galactose present and a reduction in blood-group-P, inhibitory activity. The serological activity of the glycoprotein was unaffected by treatment with pronase or papain.P, substance has receptors for the agglutinins from Salmo trutta, Clupm harengus, Soja hispida, Maclura aurantiaca and Triticum vulgaris. Some loss of receptor for Soja hispida and Maclura aurantiaca occurred after ol-D-galactosidase treatment.The structural immunochemistry of the P bloodgroup system of human erythrocytes has not yet been elucidated, although, in common with the ABO system, blood-group-active substances of heterologous origin are available and have provided insight into cross-reactive antigens. Cameron and Staveley [I] reported that hydatid-cyst fluid from sheep carrying tapeworm parasites (Echinococcus granulosus) had potent P, inhibitory activity. Freezedried hydatid-cyst fluid was extracted with phenol, by the procedure used to extract blood-group materials from human ovarian-cyst fluid. The resultant glycoprotein was reported to be similar in composition to human ovarian-cyst blood-group substances [2].Serological studies demonstrated strong specific PI inhibitory activity and indicated the importance of a-D-galactosyl groupings in P, blood-group activity We are reporting additional observations relating to the structure and serological characteristics of the P, active glycoprotein.
~31.