Galactosyltransferases Catalyzing the Formation of the Galactosyl-Galactosyl Linkage in Glycosphingolipids

摘要: Abstract Galactosyltransferases that catalyze the transfer of galactose from UDP-galactose to galactosylceramide, lactosylceramide, and ganglioside GalNAcβ1 →4(NANα2 →3)-Galβ1 →4Glc →ceramide (Gm2) were measured in rat tissues as a function development; subcellular distribution these enzymes was also determined. The novel galactosyltransferase catalyzing galactosylceramide has been characterized. enzyme attached terminal an α linkage; it required Mn2+ for activity showed pH optimum 6.0. detected extracts obtained kidney, but not any other tissue tested. attaching triglycosylceramide studied. anomeric configuration found be α. Since two transferases are both active with acceptor lipids containing β-galactosyl units, substrate specificities must defined by structure larger than ultimate glycosyl unit. These differentiated third Gm2. High activities this demonstrated spleen liver. A relationship between concentration detergent optimal reaction rate found. In view finding, limited value classical kinetics examination glycolipid is emphasized.