Carbohydrates present in the glycoprotein from conidia of the opportunistic pathogen Scedosporium prolificans

Hot aqueous extraction of conidia of Scedosporium prolificans gave a heterogeneous glycoprotein (RMP-Sp-Coni) with 41% protein and 2MeRha, Rha, Ara, Man, Gal, Glc, and GlcNH2 in a 2:18:3:47:9:15:6 M ratio, the first report of 2-O-methylrhamnose in fungi. Methylation analysis showed nonreducing end- (10%), 2-O- (11%), and 3-O-substituted Rhap (7%), nonreducing end- (8%), 2-O- (12%), 3-O- (16%), and 2,6-di-O-substituted Manp (9%), nonreducing end- (4%), 3-O- (7%), and 4-O-substituted Glcp (7%), and nonreducing end-units of Galp (9%). Mild reductive β-elimination of RMP-Sp-Coni cleaved O-linked structures to give a mixture of oligosaccharides, of which 2MeRha capping groups were present in 2MeRhaRha2Hex2Hex-ol, 2MeRhaRha2Hex-Hex-ol, 2MeRhaRha2HexHex-ol, and 2MeRhaRha2Hex-ol (ESI-MS–MS). The mixture was fractionated by Biogel P-2 column chromatography and the two predominant isolates were β-d-Galp-(1 → 6)-[2Me-α-l-Rhap-(1 → 3)-α-l-Rhap-(1 → 3)-α-d-Manp-(1 → 2)]-d-Man-ol, and another lacking the β-Galp unit. Neither was formed from mycelial glycoprotein, although β-d-Galp-(1 → 6)-[α-l-Rhap-(1 → 3)-α-l-Rhap-(1 → 3)-α-d-Manp-(1 → 2)]-d-Man-ol was a common component.