Alexander S. Shashkov

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A fucoidan fraction consisting of L-fucose, sulfate, and acetate in a molar proportion of 1:1.21:0.08 was isolated from the brown seaweed Fucus distichus collected from the Barents Sea. The 13C NMR spectrum of the fraction was typical of regular polysaccharides containing disaccharide repeating units. According to 1D and 2D 1H and 13C NMR spectra, the(More)
A fucoidan consisting of L-fucose, sulfate and acetate in a molar proportion of 1:1.23:0.36 was isolated from the Pacific brown seaweed Fucus evanescens. The structures of its desulfated and de-O-acetylated derivatives were investigated by 1D and 2D (1)H and (13)C NMR spectroscopy, and the data obtained were confirmed by methylation analysis of the native(More)
A computerised approach to the structural analysis of unbranched regular polysaccharides is described, which is based on an evaluation of the 13C-n.m.r. spectra for all possible primary structures within the additive scheme starting from the chemical shifts of the 13C resonances of the constituent monosaccharides and the average values of the glycosylation(More)
Fucoidan fractions from the brown seaweed Chorda filum were studied using solvolytic desulfation. Methylation analysis and NMR spectroscopy were applied for native and desulfated polysaccharides. Homofucan sulfate from C. filum was shown to contain poly-alpha-(1-->3)-fucopyranoside backbone with a high degree of branching, mainly of alpha-(1-->2)-linked(More)
The polysaccharide composition of a fucoidan preparation isolated from the brown alga Saccharina latissima (formerly Laminaria saccharina) was reinvestigated. The preparation was fractionated by anion-exchange chromatography, and the fractions obtained were analyzed by chemical methods combined with NMR spectroscopy. Several 2D procedures, including HSQC,(More)
Data on the structures of cell wall teichoic acids, the anionic carbohydrate-containing polymers, found in many Gram-positive bacteria have been summarized and the polymers of the actinomycete genus Nocardiopsis have been considered from the taxonomic standpoint. The structures of these polymers or their combinations have been demonstrated to be indicative(More)
The structural and genetic organization of the Escherichia coli O52 O antigen was studied. As identified by sugar and methylation analysis and nuclear magnetic resonance spectroscopy, the O antigen of E. coli O52 has a partially O-acetylated disaccharide repeating unit (O unit) containing D-fucofuranose and 6-deoxy-D-manno-heptopyranose, as well as a minor(More)
A specific acidic polysaccharide has been isolated from the Shigella boydii type 14 antigenic lipopolysaccharide after mild hydrolysis followed by chromatography on Sephadex G-50. The polysaccharide consists of the D-glucuronic acid, 2-acetamido-2-deoxy-D-glucose and D-galactose residues in the ratio 1:1:3. From the results of methylation analysis and(More)
The O-specific polysaccharide (O-antigen) structure of a Shigella flexneri type 4a strain from the Dysentery Reference Laboratory (London, UK) was elucidated in 1978 and its characteristic feature was found to be alpha-D-glucosylation of GlcNAc at position 6, which defines O-factor IV. Our NMR spectroscopic studies of the O-specific polysaccharides of two(More)