Codium latum

P-Mannan is water-insoluble and solubilizing it requires very strong alkali, cuprammonium or derivatization. X-ray and electron diffraction show that mannan has a ribbon-like conformation, similar to cellulose, with the 2-OH axial instead of equatorial. In seeds (palm, coffee, caraway) a few (<5%) of a-Gal groups are attached to the hydroxymethyl and in seaweeds a small percentage (<5) of Glc residues may occur in the chain. A pure P(l-4) mannan has been extracted from cell walls of the siphonous green alga Codium latum as the methylol mannan with paraformaldehyde dimethylsulphoxide. It was purified by size exclusion chromatography in dimethyl sulphoxide and recovered by the addition of water or methanol and could be re-dissolved in hot dimethyl sulphoxide. Infra-red and n.m.r. spectroscopy and periodate oxidation confirmed the unbranched P(l-4) structure [185]. 

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