Isolation and characterization of glycoproteins from the yeast Cryptococcus laurentii var. laurentii - II. Extracellular glycoproteins

The extracellular polysaccharide mixture of Cryptococcus laurentii var. lau rentii was fractionated into three chemically distinct heteroglycans by dif ferential precipitation. The compositional analysis of glucuronoxylomannan (GXM) revealed D-mannose (48.8 %), D-xylose (43.8 %), and D-glucuronic acid (7.4 %). It contained 2.3 % protein, 2.1 % phosphorus, and had relative mo lecular mass 2.4 x 10(6). The glucomannan (GM) contained 6.5 % protein, 1.0 % phosphorus, and consisted of D-mannose (94.2 %) and D-glucose (5.2 %). T he relative molecular mass was determined to be 4.5 x 10(4). The galactoglu coxylomannan (GalGXM) was composed Of D-mannose (70.1 %), D-galactose (18.0 %), D-glucose (5.7 %), and D-xylose (6.3 %). It contained 6.5 % protein, 0 .7 % phosphorus, and had relative molecular mass 1.9 x 10(4). The results o f structural analyses of the extracellular glycoproteins showed 1,6-linked alpha -D-mannopyranan backbone of GM and GalGXM, and 1,3-linked backbone of GXM.