STUDIES ON SYNTHETIC PATHWAY OF XYLOSE-CONTAINING N-LINKED OLIGOSACCHARIDES DEDUCED FROM SUBSTRATE SPECIFICITIES OF THE PROCESSING ENZYMES IN SYCAMORE CELLS (ACER-PSEUDOPLATANUS L)

We measured the activities of alpha-1,3-mannosyl-glycoprotein beta-1,2-N-acetylglucosaminyltransferase, alpha-1,6-mannosyl-glycoprotein beta-1,2-N-acetylglucosaminyltransferase, beta-1,4-mannosyl-glycoprotein beta-1,2-xylosyltransferase and glycoprotein 3-alpha-L-fucosyltransferase in the Golgi fraction of suspension-cultured cells of sycamore (Acer pseudoplatanus L.) using fluorescence-labelled oligosaccharides as acceptor substrates for these transferase reactions. The structures of the pyridylaminated oligosaccharides produced by these reactions were analyzed by two-dimensional sugar mapping using high-performance liquid chromatography. We demonstrated that [GRAPHICS] was processed to produce [GRAPHICS] by these in vitro reactions. On the basis of these results, we discuss a biosynthetic pathway for xylose containing N-linked oligosaccharides in plant glycoproteins.