A Revised Structure for the Forssman Glycolipid Hapten

Abstract

Abstract A glycolipid hapten of the Forssman antigen of horse spleen was found to be a ceramide pentasaccharide, which contained 2 moles of N-acetylgalactosamine, 2 moles of galactose, and 1 mole of glucose per ceramide. An α-N-acetylgalactosaminidase of hog liver (Weissman, B., and Hinrichsen, D. F., Biochemistry, 8, 2034 (1969)) hydrolyzed the terminal α-N-acetylgalactosaminosyl residue with a simultaneous loss of the Forssman hapten activity. The resulting compound was identical with globoside (Yamakawa, T., Nishimura, S., and Kamimura, H., Jap. J. Exp. Med., 35, 201 (1965); Hakomori, S., Siddiqui, B., Li, Y. T., Li, S. C., and Hellerqvist, C. G., J. Biol. Chem. 246, 2271 (1971)) and gave a specific precipitin reaction with anti-globoside antiserum. The oligosaccharide released from the Forssman hapten gave an intense Morgan-Elson reaction and 1 of the 2 moles of galactosamine was periodate resistant. With these results and those of methylation studies, the structure of Forssman hapten was proposed as N-acetylgalactosaminosyl-α-(1 → 3) N-acetylgalactosaminosyl-β-(1 → 3)galactopyranosyl-α-(1 → 4)galactopyranosyl-β-(1 → 4)glucopyranosyl-(1 → 1)ceramide.