Structures of phosphonogalactomannans isolated from mycelia of Aspergillus versicolor

The phosphonogalactomannans of Aspergillus versicolor mycelia of various ages were isolated via hot alkaline extraction followed by gel filtration chromatography. Their complex structures were determined mainly by 31P, 1H, and 13C NMR spectroscopy (400 MHz in respect to proton), and methylation analysis. The polysaccharides contained 2-O-, 6-O-, and 2,6-di-O-substituted α-mannopyranosyl units, principally in the core, and these were substituted at O-2 and O-6 with side chains of (1→5)-linked β-galactofuranosyl units, which became shorter with increasing culture age. NMR data suggested that phosphorodiester groups were present principally as bridges between C-1 of units of α-mannopyranose and C-6 of those of 5-O-substituted β-galactofuranose. Present in earlier stages of growth were very small amounts of α-mannopyranosyl and/or β-galactofuranosyl nonreducing end-units phosphorylated at HO-6. Also 6-phosphorylated were 2-O-substituted β-galactofuranosyl-(1→ groups involved in phosphorodiester bridges. Each phosphorylated structure was from side chains and was gradually removed with culture age. The youngest mycelial preparation contained small amounts of glycogen.