The 5-O-β-d-Galactofuranosyl-containing Exocellular Glycopeptide of Penicillium charlesii

Abstract

This and the succeeding paper report the structural properties of the major exocellular glycopeptide produced by Penicillium charlesii on shake culture.Treatment of the purified glycopeptide with 0.4 N NaOH resulted in the formation of mono-, di-, tri-, and polysaccharide fractions which were separated by gel permeation chromatography.The polysaccharide was characterized by: (a) methylation and gas-liquid chromatography-mass spectrometry of the products, (b) acetolysis followed by separating the products on a Bio-Gel P-2 column, and (c) Smith degradation followed by separation and identification of glycerol and threitol by gasliquid chromatography.These investigations show that the polysaccharide (phosphogalactomannan) contains approximately 90 mannopyranosyl residues and a variable number of galactofuranosyl residues.Acetolysis resulted in the formation of mannopentaose, mannotetraose, mannotriose, mannobiose, and mannose in the ratio of 2: 11:4: 5 : 13, respectively.Analysis of the methylated products and nuclear magnetic resonance studies indicate that the mannopyranosyl residues are linked to one another primarily through a( 1+2)and cr(l-+6)0-glycosidic linkages.The glycopeptide also contains 8 to 10 polygalactofuranosyl chains of variable length, each of which is attached to the C-3 atom of a mannopyranosyl residue.Each galactofuranoside is attached by p(l +5)0-glycosidic linkage to the adjoinng galactofuranosyl residue.The polymer contains 9 to 10 phosphorus atoms per mole, and they occur in the mannan as