Studies on the uronic acid-containing glycoproteins of Fusarium sp. M7-1: I. Isolation and some properties of the glycoproteins

An acidic heteropolysaccharide preparation derived from the mycelium of Fusarium sp. M7-1 was fractionated into two fractions, precipitable and nonprecipitable, by treatment with cetyltrimethylammonium bromide (Cetavlon). These two fractions were further purified to apparent homogeneity on ultracentrifugation by treatment with charcoal and gel filtration chromatographies. Two glycoproteins, precipitable GP I and nonprecipitable GP II, were obtained. The molecular weighs of GP I and GP II were estimated to be about 8.8×10⁴ and 3.7×10⁴ respectively, on gel filtration chromatography. Both GP I and GP II contained a high proportion of serine and threonine. Treatment of GP I and GP II with alkaline solution resulted in an increase in absorbance at 240 nm. Alkaline borohydride treatment markedly decreased the number of Beryl and threonyl residues and resulted in an increase in alanine and the formation of 2-aminobutyric acid. It also resulted in release of low and high molecular weight carbohydrate chains. From these results, we conclude that both GP I and GP II are glycoproteins with carbohydrate chains attached to the protein moiety through O-glycosidic linkages to the hydroxyl group of serine and/or threonine.