ISSN:
1574-6968
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
The cultured photobiont Trebouxia sp. of Ramalina celastri was successively extracted at 100°C with hot water, 2% aqueous KOH, and 10% aqueous KOH to give polysaccharide-containing fractions A (2.9%), B (3.9%), and C (0.9% yield) respectively. The intact biont contained 3.8% amylose, which was present in each fraction, and was identified by a blue color formed with iodine solution. In fraction A, and following retrogradation from aqueous solution, it was characterized by 13C-NMR spectroscopy. Fraction B was treated with α-amylase to give a water-soluble fraction consisting mainly of β-mannose-containing polysaccharides (1.5% yield), whose main component had dn/dc 0.162 and Mr 17 kDa. Fraction C was subjected to freeze–thawing and the precipitate was treated with α-amylase to give a resistant, linear, low molecular mass (1→4)-linked β-xylan. The β-d-mannopyranan preparation contained mainly of 3-O- (28%), 4-O- (11%), and 6-O-substituted Manp units (35%), with 3-O-substituted Rhap units (11%). A controlled Smith degradation provided a β-mannan with nonreducing end- (8%), 3-O- (85%) and 6-O-substituted units, showing (1→3)- and (1→6)-linked structures in the original polysaccharide. These could be present as block-type structures.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1016/S0378-1097(03)00066-1
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