Phosphates, bacterial polysaccharides

Some sugar residues in bacterial polysaccharides are etherified with lactic acid. The biosynthesis of these involves C)-alkylation, by reaction with enol-pyruvate phosphate, to an enol ether (34) of pyruvic acid, followed by reduction to the (R) or (5) form of the lactic acid ether (35). The enol ether may also react in a different manner, giving a cyclic acetal (36) of pyruvic acid. 

One of the recent fundamental advances in carbohydrate chemistry has been enzymic synthesis in vtiro this has now been realized with dextran8 and with levan.8 However, since phosphate sugars are not involved in the enzymic syntheses of these two bacterial polysaccharides, it is obvious that phosphorylation is just one process for the natural synthesis of polysaccharides. 

D-aZbacterial polysaccharides.174- 176(al Plants show heptulokinase activity176 1 the purification of D-aZfro-heptulose phosphate from Sedum spectabile has been described.176 1 The occurrence of D-wumno-heptulose phosphate in... 

Bacterial polysaccharides frequently contain D-ribofuranosyl residues as components of their polymeric chains. D-Ribulose S-phosphate was shown to serve as a precursor for the D-ribofuranosyl units in Salmonella T1 antigen,224 but details of the enzymic reactions and the nature of the activated... 

D-Galacturonic acid has also been found in bacterial polysaccharides.125,126 In several Proteus O-antigens, amino acids are amide-linked to the carboxyl group of a-D-galacturonic127 or glucuronic acid.128 It has been shown that D-galacturonic acid replaces phosphate residues in the lipid A component of the lipopolysaccharide (LPS) from the bacterium Aquifex pyrophilus,129... 

Heptoses, chromatography of, 287-289 from bacterial polysaccharide, 302 in bacteria, 286, 287 methylated, 288 periodate oxidation of, 288, 289 —> n-glyeero-D-galacto-, 320 —, v-glycero-D-manno-, 288, 320 —, D-glycero-L-numno-, 287, 319, 320, 326 —, h-glycero-v-manno-, 277, 278, 310, 320 Heptulose, D-altro-, 286 1,7-diphosphate, 240-248, 255 7-phosphate, 241-245, 247 —, o-manno 286 Heptulosonic acid, 3-deoxy-, 251 —, 3-deoxy-D-am5t o-, determination of, 252... 

Phosphopolysaccharides (polysaccharide phosphate esters) of this kind occur frequently in living systems and in a number of important technological products. Many bacterial polysaccharides contain phosphate ester groups. In these the phosphate groups serve to link the saccharide rings to lipids or other biopolymer units as, for example, in the teichoic acids (Section 10.3). Phosphorylation is known to profoundly affect food properties (Chapter 12.4). 

Methods have been developed to reveal the presence and the position of phosphate ester moieties on sugars. Phosphorylated sugar constituents, e KDO, heptoses and glucosamine, in bacterial polysaccharides were detected by comparison... 

Tarr and Hibbert13 published the first detailed study of the formation of bacterial cellulose. A systematic series of experiments, conducted with a view to obtaining a culture medium which did not support visible growth of A. xylinum until a suitable source of carbon was added, indicated that a solution (pH 5.0) containing 0.1% asparagine, 0.5% potassium dihydrogen phosphate, 0.1% sodium chloride and 0.5% ethanol satisfied these requirements. Maximum polysaccharide formation oc-... 

A bacterial phosphatidylinositol specific phospholipase C (PI-PLC) had been available for many years before it was demonstrated to strip a number of membrane-bound proteins from eukaryotic cell surfaces [1], Such proteins are anchored by a PI moiety in which the 6 position of inositol is glycosidically linked to glucosamine, which in turn is bonded to a polymannan backbone (Fig. 3-10). The polysaccharide chain is joined to the carboxyl terminal of the anchored protein via amide linkage to ethanolamine phosphate. The presence of a free NH2 group in the glucosamine residue makes the structure labile to nitrous acid. Bacterial PI-PLC hydrolyzes the bond between DAG and phosphati-dylinositols, releasing the water-soluble protein polysac charide-inositol phosphate moiety. These proteins are tethered by glycosylphosphatidylinositol (GPI) anchors. 

The outer surfaces of bacteria are rich in specialized polysaccharides. These are often synthesized while attached to lipid membrane anchors as indicated in a general way in Eq. 20-20.136/296a One of the specific biosynthetic cycles (Fig. 20-9) that depends upon undeca-prenol phosphate is the formation of the peptidoglycan (murein) layer (Fig. 8-29) of both gram-negative and gram-positive bacterial cell walls. Synthesis begins with attachment of L-alanine to the OH of the lactyl... 

The sugar nucleotides (an uninformative name that has been used for glycosyl nucleotides, or more strictly, glycosyl esters of nucleoside di- or mono-phosphates) were discussed in this Series12 in 1973. Since then, accumulation of new data about these derivatives has continued, and now, about 35 representatives of this class are known to participate in the biosynthesis of polysaccharide chains of bacterial polymers (for a survey, see Ref. 13). These include glycosyl esters of uridine 5 -diphosphate (UDP), thymidine 5 -diphosphate (dTDP), guanosine 5 -diphosphate (GDP), cytidine 5 -diphosphate (CDP), cytidine 5 -monophosphate (CMP), and adenosine 5 -diphosphate (ADP). 

Two of the most frequent monosaccharide components of bacterial polymers belonging to this group have been the subjects of articles in this Series. They are 3-deoxy-D-manno-2-octulosonic acid,247 a normal constituent of the core region of bacterial lipopolysaccharides that is also present in some other polymers, and N-acetylneuraminic acid,248 found in several capsular polysaccharides. Enolpyruvate phosphate serves as the precursor of the C-l-C-3 fragment of the monosaccharides, with D-arabinose 5-phosphate or 2-acetamido-2-deoxy-D-mannose 6-phosphate being an acceptor for transfer of the three-carbon unit. Characteristic, activated forms of these monosaccharides are the CMP derivatives. 

Polysaccharide-1-phosphates were extracted in some cases from bacterial cell walls. For example, TA isolated from Staphylococcus lactis 2102 consists of ca. 23 monomeric fragments each built of a-D-N-acetylglucosamine-1 -phosphate 22). These units are linked by the phosphoester bond at the 6 position in the sugar residue, as represented by 7. 

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