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 1 H and 13 C spectra of the polysaccharide involved a combination of 2D NMR experiments including double‐quantum‐filtered { 1 H, 1 H} COSY, { 1 H, 1 H} TOCSY and 1 H‐detected { 1 H, 13 C} heteronuclear multiple quantum coherence spectroscopy. The sequence of the glycosyl residues, including the linkage positions, was deduced by { 1 H, 1 H} 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:.