A new arabinomannan from the cell wall of the chlorococcal algae Chlorella vulgaris

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• 作者：Susanne Pieper^a ; Inga Unterieser^a ; Florian Mann^b ; Petra Mischnick^a ; ^{p.mischnick@tu-braunschweig.de}
• 关键词：Chlorococcal algae ; Chlorella vulgaris ; Cell wall polysaccharide ; Arabinomannan ; Polysaccharide structure ; Electrospray ionisation mass spectrometry/collision induced dissociation (ESI&ndash ; MS/CID)
• 刊名：Carbohydrate Research
• 出版年：2012
• 出版时间：1 May, 2012
• 年：2012
• 卷：352
• 期：Complete
• 页码：166-176
• 全文大小：1000 K

文摘

A new arabinomannan has been isolated from the cell wall of the green algae Chlorella vulgaris by extraction with 0.1 M NaOH, dialysis and SEC fractionation. M_w was about 8000 u. Terminal, 2- and 5-O-linked arabinofuranosyl residues, and 2,6-O-linked mannopyranosyl residues were detected as the main constituents beside some minor mannose components by methylation analysis. Electrospray ionisation mass spectrometry (ESI-MS) with collision induced dissociation (CID) up to MS³ experiments of oligosaccharides obtained by partial methanolysis or partial acid hydrolysis indicated the presence of Man¡úMan- and Ara¡úAra- as well as Ara¡úMan- and also Man¡úAra-sequences. MS² experiments gave evidence of a (1?)-linked mannan, probably also including some (1?)-linked mannosyl and 5-linked arabinofuranosyl residues. Mannooligosaccharides up to DP5 with mainly (1?)-, but at higher DP also (1?)-linkages were obtained by acid hydrolysis, and arabino oligomers up to DP4 could be detected after mild methanolysis. In accordance with results from methylation analysis and ESI-MS/CID t-¦Â-Araf, 2-¦Á-Araf, 5-¦Á-Araf and 2,6-¦Á-Manp were identified from homo- and heteronuclear 1D- and 2D NMR experiments in a molar ratio of ?:2:1:2. A highly branched structure is suggested with a 6- and 2-O-linked mannan main chain, comprising 5-Araf residues. Araf-¦Â-[(1?)-Araf-¦Á-(1¡ú]_n side chains with an average chain length of 2 are linked to the mannan main chain. The configuration of Ara is d. The new polysaccharide shows structural similarities with the (lipo)arabinomannans of Mycobacterium tuberculosis.