Structure of some sulfated sugars isolated after acid hydrolysis of the extracellular polysaccharide of Porphyridium sp., a unicellular red alga
✍ Scribed by Niculina Lupescu; Shoshana (Malis) Arad; Shimona Geresh; Michael A. Bernstein; Robert Glaser
- Publisher
- Elsevier Science
- Year
- 1991
- Tongue
- English
- Weight
- 251 KB
- Volume
- 210
- Category
- Article
- ISSN
- 0008-6215
No coin nor oath required. For personal study only.
✦ Synopsis
Several polysaccharides isolated from red, brown, and green seaweeds', and from unicellular green and red algae', were found to be sulfated. In determining the structure of the extracellular sulfated polysaccharide produced by the unicellular marine red alga Porphyridium sp., sulfated sugars were isolated in addition to the reported aldobiouronic acid3m6 and neutral sugars. The aldobiouronic acid [3-O-(a-D-glucopyranosyluronic acid)-L-galactopyranose] is a basic building block of the polysaccharides of various unicellular red algae (the marine algae P. sp. and P. cruentum, the fresh-water alga P. aerugineum, and the brackish-water alga Rhodella reticuZata)3mh. Evidence is now reported for the structure of three of the sulfated sugars.
Mild hydrolysis (0.1~ trifluoroacetic acid, 3 h, 100°) of the polysaccharide followed by elution from resin DE-52 with 0.5~ NH,HCO, gave a charged fraction which was then subjected to gel filtration on Sephadex G-10. One of the fractions (A) showed (t.1 .c., silica gel) components whose R, values were commensurate with anionic monosaccharides, but were higher than those noted for oligo-and di-saccharides having carboxylate groups. Fraction A had i.r. absorbances typical of sulfate half-esters.
Desulfation of fraction A by acid hydrolysis, followed by borohydride reduction, and acetylation gave (g.1.c.) mainly acetylated xylitol, glucitol and galactitol in the ratios -1.0:2.6:0.8. Chromatography on Bio-gel P-2 of fraction A gave a later sub-fraction, which represented 1% of the total carbohydrates (phenol-sulfuric acid method)' of the native polysaccharide, and had i.r. bands at 820, 823, and 870 cm-' (C-0-S bending), and 1238 and 1258 cm-' (S = 0 stretching, broad). The molar ratio of carbohydrate (phe-nol&ulfuric acid method)' and sulfate (sodium rhodizonate method