Structural characterization of the cell wall d-glucans isolated from the mycelium of Botryosphaeria rhodina MAMB-05

Three d-glucans were isolated from the mycelium of the fungus Botryosphaeria rhodina MAMB-05 by sequential extraction with hot-water and hot aqueous KOH (2% w/v) followed by ethanol precipitation. Following their purification by gel permeation chromatography on Sepharose CL-4B, the structural characteristics of the d-glucans were determined by FT-IR and 13C NMR spectroscopy and, after methylation, by GC–MS. The hot-water extract produced a fraction designated Q1A that was a β-(1→6)-d-glucan with the following structure:Figure optionsDownload full-size imageDownload as PowerPoint slideThe alkaline extract, when subjected to repeated freeze–thawing, yielded two fractions: K1P (insoluble) that comprised a β-(1→3)-d-glucan with β-d-glucose branches at C-6 with the structure:Figure optionsDownload full-size imageDownload as PowerPoint slideand K1SA (soluble) consisting of a backbone chain of α-(1→4)-linked d-glucopyranosyl residues substituted at O-6 with α-d-glucopyranosyl residues:Figure optionsDownload full-size imageDownload as PowerPoint slide

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