Helmut Weigel

Complexes of copper(II), calcium, and other metal ions with carbohydrates: Thin-layer ligand-exchange chromatography and determination of relative stabilities of complexes

Abstract Thin-layer ligand-exchange chromatography with sodium, magnesium, aluminium, calcium, chromium(III), iron(III), nickel, copper(II), zinc, strontium, cadmium, and barium as the central atoms has been investigated. With copper(II) as the central atom, the method is a simple, inexpensive, and speedy means of resolution of mixtures of carbohydrates not easily achieved by other methods. The molar ratios of complexed to uncomplexed polyhydroxy compounds, which give an indication of the relative stabilities of the complexes, are calculated from the chromatographic migration rates. For a particular compound, this ratio is, in general, greatest for the complex with the copper(II) ion.

Chemistry of the polysaccharides of the diatom Coscinodiscus nobilis

Abstract The extracellular polysaccharide of Coscinodiscus nobilis , a member of the Coscinodiscaceae, contains a highly branched heteropolysaccharide(s) containing fucose, rhamnose, mannose, d -glucose, xylose, d -glucuronic acid, galactose (trace) and half ester sulphate. The positions of linkages between the monosaccharides have been established and evidence for the linkages between d -glucuronic acid and monosaccharides was obtained. The extracellular polysaccharide contained also a chrysolaminaran, but this may have been derived from dead cells. Fucose and mannose occur also in a separate polymer. The diatom contained polysaccharide material consisting of glucose, mannose, fucose and uronic acid residues.

Structure of the levan elaborated by Streptococcus salivarius strain 51: An application of chemical-ionisation mass-spectrometry

The polysaccharide elaborated by Streptococcus salivarius strain 51 contains beta-D-fructofuranose residues linked through positions 2 and 6, as well as 1, 2, and 6. The approximate numbers of terminal, non-reducing D-fructofuranose residues and those linked through positions 2 and 6, and through 1, 2, and 6 in the average repeating-unit are 1, 7, and 1, respectively. The branches through the beta-(2 leads to 1)-linkage contain up to at least four D-fructofuranose residues. Chemical-ionisation mass-spectrometry aids the assignment of structures to O-acetyl-O-methylalditols obtained in methylation analysis.

Studies on dextrans and dextranases : Part X. Types and percentages of secondary linkages in the dextrans elaborated by leuconostoc mesenteroides NRRL B-1299

Abstract The water-soluble (dextran S) and less water-soluble (dextran L) dextrans elaborated by Leuconostoc mesenteroides NRRL B-1299 contain α- d -glucopyranose residues linked through positions 1 and 6, 1 and 3, as well as 1, 2, and 6. The approximate number of terminal non-reducing d -glucose residues and those linked through positions 1 and 6, 1 and 3, as well as 1, 2, and 6 in the average repeating-unit of dextran S are 5, 4, 1, and 5. The corresponding figures for dextran L are 5, 4, 3, and 5.

Studies on dextrans and dextranases : Part IX. Dextrans elaborated by cariogenic organisms

Abstract The cariogenic Streptococcus Ingbritt and S. OMZ 51 and the non-cariogenic S. ATCC 10558 produce polysaccharides, the major component of which is of the dextran type. A high proportion of the glucose residues in the dextran-like materials are linked through non-α- D -(1→6) linkages. The number of “anhydro-glucose” units in the average repeating-units of these materials ranges from 4 to 11. It is likely that the non-α- D -(1→6) linkages form branch points. The methods used failed to reveal significant structural differences between the dextran-like materials produced by cariogenic and non-cariogenic organisms.

Complexes between polyhydroxy compounds and copper(II) ions

Abstract Several polyhydroxy compounds have been shown to form cationic complexes with copper(II) ions. Paper electrophoresis in copper(II) acetate and basic co

Studies on dextrans and dextranases : Part XI. The structure of a dextran elaborated by Leuconostoc mesenteroides NRRL B-1299

Abstract In dextran S elaborated by Leuconostoc mesenteroides NRRL B-1299, the polymeric chain consists, principally, of segments of isomaltose homologues which are mutually linked through positions 1 and 2 of their terminal D -glucose residues. The average repeating-unit, containing a total of fifteen D -glucose residues, possesses five branches which occur at each position 6 of such segments and at positions 2. Branches consist mainly of α- D -glucopyranosyl groups and some appear to be terminated by α-nigerosyl groups.

Chromatography of polyhydroxy compounds on cellulose impregnated with tungstate: determination of pseudo-stability constants of complexes

Abstract Impregnation of cellulose with tungstate affects the chromatographic migration rates of a number of polyhydroxy compounds, offering a means, on small and large scales, of resolution of mixtures not easily achieved by other methods. The effects have been correlated with the structure of the polyhydroxy compounds and their tungstate complexes. Pseudo-stability constants of the complexes have been determined.

Structural studies of the water-soluble fucan from lessonia nigrescens

Abstract Partial hydrolysis of the water-soluble “fucan” from Lessonia nigrescens gave monosaccharides, neutral and acidic oligosaccharides, a soluble polymer, and an insoluble residue. The neutral oligosaccharides, consisting solely of galactose, were separated into six fractions. The eight acidic oligosaccharides were inseparable mixtures, of which two were shown to contain glucuronic acid and fucose and the remainder to contain all the monosaccharides present in the original polysaccharide. The soluble polymer, which comprised 20% of the starting material and had a molecular weight of ∼8000, had an acid stability and n.m.r. spectrum indicative of a linear polymer of ∼44 alternating units of glucuronic acid and mannose.

Interaction between polyhydroxy compounds and vanadate ions: electrophoresis and composition of complexes

Abstract Several polyhydroxy compounds form anionic complexes with vanadate ions. The V/polyol ratio in several complexes has been determined. In the pH range 5–9.5, the complexing agent is likely to be a metavanadate ion, (VO) n n- . Electrophoresis in sodium metavanadate solution is particularly useful for the separation of hexitols, hex-2-uloses, and several disaccharides.