Linear mannan and branched phosphomannan were identified as exopolysaccharides produced by Kuraishia capsulata yeast. Their structures were determined using nuclear magnetic resonance spectroscopy. The repeating unit of mannan was found to be a trisaccharide →6)-α-Manp-(1→2)-α-Manp-(1→2)-α-Manp-(1→, while the phosphomannan was shown to be built of β-Manp-(1→2)-α-Manp-(1 disaccharide blocks linked by phosphodiester bonds via C-1 and C-6 of the reducing unit. The production of both polysaccharides was shown to depend on the phosphate concentration in the culture medium. In the absence of phosphate, only mannan was obtained, while an excess of KH2PO4 led to the exclusive production of phosphomannan. Chemical depolymerisation of phosphomannan led to the formation of disaccharide β-Manp-(1→2)-(6-P)-Manp, representing the repeating unit of the hydrolysed polysaccharide. The treatment of the disaccharide with alkaline phosphatase resulted in the formation of disaccharide β-Manp-(1→2)-Manp. The latest products can be transformed into glycosyl donors applicable further in the synthesis of oligosaccharides related to Candida cell wall polysaccharides.
structure, mannan, phosphomannan, Kuraishia capsulata, Depolymerisation, De-O-phosphorylation
NCBI PubMed ID: 29254015Publication DOI: 10.1016/j.carbpol.2017.11.103Journal NLM ID: 8307156Publisher: Elsevier
Correspondence: Nifantiev NE
Institutions: N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Moscow, Russia
Methods: 13C NMR, 1H NMR, dephosphorylation, ESI-MS, ROESY, TOCSY, trifluoroacetic acid solvolysis, HMBC, COSY, HSQC, HP-SEC
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