title: Sialylation of lacto-N-neohexaosylceramide by sialyltransferase from embryonic chicken muscle.
abstract: A sialyltransferase which catalyzes the in vitro biosynthesis of N-acetylneuraminosyllacto-N-neohexaosylceramide from lacto-N-neohexaosylceramide and CMP-NeuAc has been examined in embryonic chicken breast muscle. The maximum enzyme activity was observed in 11-12-day-old embryos. The enzyme has optimum activity at pH 6.8 in the presence of Triton CF-54 and Mg2+. The apparent Km values for lacto-N-neohexaosylceramide and CMP-NeuAc were 0.9 and 0.67 mM, respectively. The enzymic product was characterized by TLC, neuraminidase hydrolysis and permethylation analysis. The structure was identical to authentic N-acetylneuraminosyllacto-N-neohexaosylceramide from chicken muscle. In addition, a disialo derivative has been detected that constitutes 15% of the total radioactivity incorporated. The two sialic acids connected by sialosyl-sialosyl linkage were attached to the terminal galactose residue. To our knowledge, this is the first report of biosynthesis of this disialo compound.
mesh_terms: D000818:Animals; D001345:Autoradiography; D002250:Carbon Radioisotopes; D002642:Chick Embryo; D002855:Chromatography, Thin Layer; D005732:Gangliosides; D006028:Glycosphingolipids / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D007425:Intracellular Membranes / Q000201:enzymology; D007700:Kinetics; D007790:Lactosylceramides / Q000096:biosynthesis / Q000378:metabolism*; D009132:Muscles / Q000201:enzymology*; D012799:Sialyltransferases / Q000378:metabolism*; D013379:Substrate Specificity; D014166:Transferases / Q000378:metabolism*
chemical_list: D002250:Carbon Radioisotopes; D005732:Gangliosides; D006028:Glycosphingolipids; D007790:Lactosylceramides; C048512:lacto-N-neohexaosylceramide; C045713:disialo-lacto-N-norhexaosyl ceramide; D014166:Transferases; D012799:Sialyltransferases