Mannuronic-guluronic acid ratio

Polysaccharides. Na-alglnate was Isolated from Laminaria Hyperbo-rea. The guluronic acid content was found to be 63.6%, corresponding to an M/G (mannuronic acid/guluronic acid) ratio of 0.57. 

Mizuno, H., Saito, T., Iso, N., Onda, N., Noda, K., andTakada, K. (1983) Mannuronic to guluronic acid ratios of alginic acids prepared from various brown seaweeds. Butt. Jap. Soc. Sci. Fish., 49, 1591-1593. 

D-Mannuronic acid (36) constitutes the major component of alginic acid, the main polysaccharide of the brown algae, in which L-guluronic acid (37) is also found. The ratio of D-mannuronic acid and L-guluronic acid can vary with the algal species, the type of tissue, and the age of the plant. In the case of Laminaria hyperborea, L-guluronic acid is the major component.130... 

For alginates, the copolymer composition (ratio of mannuronic to guluronic acid units) can influence the ultimate complex properties. These include elasticity as well as permeability and mechanical resistance of coacer-vates cast into 2D or spherical membrane structures. The type of polymer-polymer coacervate (precipitate, sol, network) will also often be highly molar mass dependent, with useful membranes formd within a narrow window. This often does not correspond to the molar mass range required for bioapplications, which is dictated by factors such as cell toxicity and biocompatability. 

The sequence and composition of uronate residues in intact alginate samples have been determined by high resolution H n.m.r. spectroscopy. Problems encountered owing to the viscosity of the samples were overcome by controlled and slight depolymerization before n.m.r. at 90 °C. The D-mannuronic acid L-guluronic acid molar ratio was obtained from the intensities of the signals from... 

Alginic acids isolated from different sources can differ in the ratio of mannuronic and guluronic acids (M/G) and in the distribution of the monomers along the polymeric chain. The size and distribution of individual blocks strongly afifect the properties of alginic acids and alginates [1]. 

Zimmermarm U, Klock G, Federhn K, Hannig K, Kowalski M, Bretzel RG, et al. Production of mitogen-contamination free alginates with variable ratios of mannuronic acid to guluronic acid by free flow electrophoresis. Electrophoresis 1992 13(5) 269-274. 

Polarimetry of the brucine salts of L-guluronic acid and D-mannuronic acid released from alginates by acid hydrolysis has been used to measure the ratio of these acids in the native alginate. Nitroxide spin-labels have been investigated as molecular probes to determine the microviscosity of aqueous solutions of carbohydrates such as alginate. ... 

A short presentation of the electrostatic interactions of acidic polysaccharides with d- and L-enantiomers of polylysine is given. As polysaccharide components pectate and alginates rich in l-guluronate and D-mannuronate, respectively were used. The results of the study by means of circular dichroism showed that the complex formation is governed by the stoichiometric ratio of the charges of both interacting components. The conformation of polysaccharide used for complexation was proved to be the decisive factor influencing the interaction efficiency. 

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