Isolation and characterization of glycoproteins from the yeast Cryptococcus laurentii .1. Cell-wall glycoproteins

Cell-wall glycoproteins were isolated by extraction with anhydrous ethylenediamine of the cell wall of the yeast Cryptococcus laurentii. The extraction yielded a water-soluble fraction A and a water-insoluble fraction B. The fraction A contained 43.3 % saccharides and 43.0 % proteins. Only 23.1 % of serine and 14.3 % of threonine residues of this fraction was glycosylated by O-linked oligosaccharides. The water-soluble glycoproteins were separated into a low-molecular mass glycoprotein containing galactose and mannose in the ratio (x(r) = 5:1) and a high-molecular mass glycoprotein fraction containing galactose, glucose, mannose, xylose, and rhamnose in the mole ratio 0.3:1.0:0.75:0.5:0.03, with traces of arabinose. N-Glycosidically linked oligosaccharides released from the high-molecular mass fraction by endoglycosidase H were characterized by molar proportion mannose:xylose: galactose:glucose: rhamnose = 2.17:0.43:0.86:1.0:0.28. The N-glycosidically linked oligosaccharides released by alkaline cleavage were characterized by molar proportion of neutral monosaccharides - mannose, xylose, galactose, glucose, and arabinose in the ratio 0.08:0.18:0.025:1.0:0.15.