Enzymatic synthesis of a blood group H-related glycosphingolipid by an alpha-fucosyltransferase from bovine spleen.

An alpha-fucosyltransferase activity has been detected in a purified membrane preparation isolated from bovine spleen which catalyzes the transfer of L-fucose from GDP-L-[14C]-fucose to a tetraglycosylceramide (Lac-nTet-cer, Galbetal-4GlcNAcbeta1-3Galbeta1-4-Glc-cer) to form the blood group H-related glycosphingolipid. The membrane preparation contained a highly active endogenous nonlipid acceptor, which could be precipitated by 5% trichloroacetic acid or chloroform-methanol-water (6:3:5, v/v/v), whereas there was little endogenous glycosphingolipid acceptor. The optimum pH value for the incorporation of L-fucose was 6.4 in cacodylate-HCl buffer. The Km values were 0.6 mM and 0.36 mM for Lac-nTet-cer and GDP-L-fucose, respectively. The 14C-labeled product of the reaction was isolated and purified; it migrated with human erythrocyte blood group H-active pentaglycosylceramide. the terminal [14C]fucose was hydrolyzed 85% and 55% by 0.1 N trichloroacetic acid at 100 degrees for 2 hours and Charonia lampas alpha-fucosidase (19 hours at 37 degrees), respectively. The 14C-labeled product inhibited the hemagglutination reaction of O-type cells against eel anti H(O) globulin and formed a precipitin line with Ulex europeus lectin.