Structure of the De‐O‐acetylated glucuronoxylomannan from Cryptococcus neoformans serotype D, as determined by 2D NMR spectroscopy

The primary structure of the de‐O‐acetylated glucuronoxylomannan isolated from Cryptococcus neoformans serotype D was characterized de novo by NMR spectroscopy. Assignment of the 1H and 13C spectra of the polysaccharide involved a combination of 2D NMR experiments including double‐quantum‐filtered {1H,1H} COSY, {1H,1H} TOCSY and 1H‐detected {1H,13C} heteronuclear multiple quantum coherence spectroscopy. The sequence of the glycosyl residues, including the linkage positions, was deduced by {1H,1H} rotating‐frame NOE (ROESY) spectroscopy. The serotype‐D glucuronoxylomannan was found to be a branched polymer with a repeating pentasaccharide unit of the following structure: magnified image .