The structure of two blood group A-active glycosphingolipids with 12 sugars and a branched chain present in the epithelial cells of rat small intestine.

Two blood group A-active dodecaglycosylceramides were earlier reported in a mixed fraction isolated from rat small intestine (Breimer, M. E., Hansson, G. C., Karlsson, K.-A., and Leffler, H. (1982) J. Biol. Chem. 257, 906-912). Treatment of these with alpha-N-acetylgalactosaminidase produced two blood group H-type decaglycosylceramides earlier identified in this tissue (Breimer, M. E., Falk, K.-E., Hansson, G. C. and Karlsson, K.-A. (1982) J. Biol. Chem. 257, 50-59). Proton NMR spectroscopy of the intact dodeca- and decaglycosylceramides and degradation studies established the following two branched-chain species, one (60% of the mixture) with type 1 sequences (Gal beta 1 leads to 3GlcNAc) in all three places, and the second (40% of the mixture) identical with this except for a type 2 sequence (Gal beta 1 leads to 4GlcNAc) in the 6-linked branch.