STRUCTURAL STUDY OF A CELL-WALL MANNAN OF SACCHAROMYCES-KLUYVERI IFO-1685 STRAIN - PRESENCE OF A BRANCHED SIDE-CHAIN AND BETA-1,2-LINKAGE

Acetolysis of the cell-wall mannan of Saccharomyces kluyveri under mil d conditions, gave fragments with 1-6 mannose residues. The structures of mannopentaose and mannohexaose were determined to be [GRAPHICS] re spectively, by two-dimensional homonuclear Hartmann-Hahn spectroscopy and a sequential NMR assignment method that combines H-1-C-13 correlat ed spectroscopy, relayed coherence transfer spectroscopy, H-1-detected heteronuclear multiple-bond connectivity and methylation analysis. Th e H1 proton chemical shift of a neighboring a-1,2-linked mannose unit of the 3-O-substituted structure was shifted upfield by the addition o f a mannose unit to the adjacent 3-O-substituted unit by an alpha-1,6 linkage. The characteristic HI-H2-correlated cross-peak of the alpha-1 ,3-linked mannose unit substituted by a beta-1,2 linkage, beta1-->2Man alpha1-->3, in the mannan of S. kluyveri, as also found by two-dimensi onal homonuclear Hartmann-Hahn spectroscopy in the mannan of Candida g uilliermondii, a pathogenic yeast in man.