The 5-O-β-d-Galactofuranosyl-containing Exocellular Glycopeptide of Penicillium charlesii: OCCURRENCE OF ETHANOLAMINE AND PARTIAL CHARACTERIZATION OF THE PEPTIDE PORTION AND THE CARBOHYDRATE-PEPTIDE LINKAGE

Abstract

Abstract The major exocellular glycopeptide (peptidophosphogalactomannan) produced by Penicillium charlesii was shown to contain 30 to 32 amino acid residues, and serine and threonine accounted for approximately 15 residues. In addition, the glycopeptide was found to contain approximately 1 ethanolamine residue per molecule. Treatment of the glycopeptide with alkali resulted in an increase in absorbance at 241 nm with the concomitant release of peptide from monosaccharides, oligosaccharides, and phosphogalactomannan. The number of seryl and threonyl residues decreased markedly following alkaline borohydride-PdCl2 treatment of the glycopeptide. This treatment also resulted in an increase in alanine and the appearance of α-aminobutyric acid after hydrolyzing the reaction mixture in 6 n HCl. In addition, treatment of the glycopeptide with alkaline NaB3H4 followed by hydrolyzing the phosphogalactomannan in 2 n HCl resulted in the formation of [3H]mannitol. We conclude that the phosphogalactomannan is attached to the peptide through O-glycosidic linkage of the terminal mannosyl residue to the hydroxyl group of serine or threonine.