Mannuronate residues, alginic acid

For example, the biosynthesis of alginate involves GDP-mannuronic acid (GDP-ManA) as NDP-Glx, bactoprenol as the lipid, and a glycosyltransferase that inserts a second mannuronate residue (as Z). 

Alginic acid is a polyuronic acid composed of residues of D-mannuronic acid and L-guluronic acid and is obtained chiefly from algae belonging to the Phaeo-phyceae, mainly species of Laminaria. 

The PhEur 2005 describes alginic acid as a mixture of polyuronic acids [(CgHgOeU composed of residues of D-mannuronic and L-glucuronic acid, and is obtained mainly from algae belonging to the Phaeophyceae. A small proportion of the carboxyl groups may be neutralized. 

Polysaccharides. The most important member of this class of polysaccharides is alginate, a polysaccharide produced by seaweed and bacteria and widely used in the food industry. It is biosynthesised initially as a p-(1 4)-linked poly-mannuronic acid, by sequential transfer from GDP mannuronate. Some of the individual mannuronate residues are then epimerised at C5 to yield a-L-guluronate residues. The conformation of these guluronate residues is disfavoured by the axial OH on C2, the anomeric effect at Cl and above all by the now-axial carboxylate at C5 the C4 conformation, with the intersaccharide linkages now 1,4-diaxial, is adopted by the guluronate residues. 

The seaweed polyglycosiduronic acid alginic acid, whichj is composed of D-mannuronic and L-guluronic acid residues, when treated with a partially purified preparation of a cell-free extract of an adapted pseudomonad, is initially depolymerized to a series of oligosaccharides each of which contains a 4-deoxy-L-er2/terminal position, and then to the h-erythro isomer of the ulosonic acid (107), which is the product formed from both of the constituent residues. 

Ficoll is a synthetic polymer of sucrose. Alginate is a linear polysaccharide from marine organisms consisting of D-mannuronic and L-guluronic acid residues. Alginate has the important property that it forms a gel in the presence of bivalent cations, like Ca ". ... 

Alginic acid is a linear copolymer with homopolymeric blocks of (l-4)-linked p-D-mannuronate (M) and its C-5 epi-mer a-L-glucuronate (G) residues, respectively, covalently linked together in different sequences or blocks. The different forms of alginic acid are represented in Figure 1.29. The monomers can appear in homopolymeric blocks of consecutive G-residues (G-blocks), consecutive M-residues (M-blocks), or alternating M- and G-residues (MG-blocks). 

Alginic acid n. Polysaccharide composed of beta D mannuronic acid residues found in certain seaweeds. 

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