Sugars lipopolysaccharide

FIGURE 8.18 Dolichol phosphate is an initiation point for the synthesis of carbohydrate polymers in animals. The analogous alcohol in bacterial systems, undecaprenol, also known as bactoprenol, consists of 11 isoprene units. Undecaprenyl phosphate delivers sugars from the cytoplasm for the synthesis of cell wall components such as peptidoglycans, lipopolysaccharides, and glycoproteins. Polyprenyl compounds also serve as the side chains of vitamin K, the ubiquinones, plastoquinones, and tocopherols (such as vitamin E). 

Shortly afterwards, Westphal, Liideritz, and their coworkers using the newly developed method of paper chromatography, found a new class of sugars in lipopolysaccharides (LPS) from Gram-negative bacteria, and identified them as 3,6-dideoxyhexoses. This work is summarized in Ref. 4. These discoveries initiated more-systematic investigations of hydrolyzates from bacterial polysaccharides, and a number of new monosaccharides were completely or partially identified. This development has been summarized by Ashwell and Hickman. ... 

Recent applications of HPAEC-PAD are many and varied. A representative list includes quantitation of polyglucose metabolites in plasma of dialysis patients,148 analysis of heat-treated milk,149 carbohydrate content in lipopolysaccharides,150 phosphorylated sugars in tissue samples,151 composition of soybean meal,152 carbohydrate composition of recombinant modified tissue plasminogen activator,153 analysis of cyclization products from an enzyme reaction,154 carbohydrate content of glycoconjugate vaccines,155 and monitoring of patients with rheumatoid arthritis.156... 

Carbohydrates related to membranes can be found as lipopolysaccharides or as parts of glycoproteins. Sugars are often characteristic determinants of cell surfaces (see below). The great majority of carbohydrates are found in the outer leaflet of a membrane, resulting in an asymmetrical structure. This is especially true for many plasma membranes and the outer membrane of Gram-negative bacterial cells (see below). 

Regioselective oxidation by brominolysis of dioxastannolane obtained from methyl / -L-ara-binopyranoside made it possible to accomplish (after subsequent oximation and reduction) a facile synthesis of 4-amino-4-deoxy-L-arabinose, an amino-sugar found in lipopolysaccharides of some Salmonella R. mutant strains <83CPB3778>. 

N. catarrhalis,560 N. perflava,559 Moraxella duplex and Micrococcus calco-aceticus,443 and Escherichia coli,420 Vicari and Kabat,45 in studies of blood-group oligosaccharides, and Hellerqvist and colleagues,53 in an examination of the common core-polysaccharide of Salmonella typhimurium, have used similar methods. The examination of amino sugars as their peracetylated aminodeoxyalditols has also been used by Liideritz and colleagues72 to establish the occurrence of 4-amino-4-deoxy-L-arabinose in Salmonella lipopolysaccharides, and has been extended to aminodeoxyheptoses by Williams and Perry.561... 

The occurrence of this group of sugar nucleotides is limited mainly to the cells of Gram-negative bacteria. Those bacterial mutants defective in lipopolysaccharide synthesis are useful for preparative isolation of such esters, as the concentration of sugar nucleotides in normal cells is very low. 

One of the most impressive findings has been the discovery of lipid intermediates in the biosynthesis of polysaccharides (see Refs. 2 and 465.) At least two structurally different types of these compounds exist the intermediate may be an isoprenoid alcohol ester of the glycosyl pyrophosphate or the analogous derivative of the glycosyl phosphate. Derivatives of the first type are formed by reaction between the sugar nucleotide and the alcohol phosphate, for example, undecaprenyl phosphate (120), which participates in the biosynthesis of Salmonella lipopolysaccharide.466... 

The 3-deoxy-D-ma/ino-2-octulosonic acid 8-phosphate synthase (KDO synthase or KdoS EC 4.1.2.16) is an enzyme involved in the biosynthesis of the eight-carbon sugar KDO [63], a constituent of the capsular polysaccharides (K-antigens) and outer membrane lipopolysaccharides (LPS, endotoxin) of Gram-negative bacteria [156], as well as of the cell wall of algae and a variety of plants [157], In vivo, the enzyme catalyzes the irreversible addition of 26 to D-arabinose 5-phosphate (Ara5P, 32) to form KDO 8-phosphate 33 [158]. The... 

O-Chains (and core structures) contain many unique or unusual sugar constituents and, in recent years, many members of different sugar classes have been identified in lipopolysaccharides (Table I). 

In Figure 1, the structures of the Ra to Re lipopolysaccharides have been indicated. These incomplete lipopolysaccharides which are devoid of O chains and parts of the core are formed by R mutant strains which are defective in the synthesis of the O chain (Ra) or of the core (Rb-Re) (reviewed by Luderitz et al., 1982). Ra to Re lipopolysaccharides represent intermediates in lipopolysaccharide biosynthesis. They express distinct serological specificities since the respective terminal sugar units act as the main immunodeterminant. The different R lipopolysaccharides and the respective R mutants, therefore, can be differentiated by serological methods. 

The most noteworthy differentiation of the lipopolysaccharides of the seven antigens is evident upon comparison of the different components present in the amino sugar fraction, as shown in Table II. All of the antigens contain 2-amino-2-deoxy-D-glucose,... 

Table II. Amino Sugar Composition of the Lipopolysaccharide Antigens of Pseudomonas aeruginosa (Relative Percentages)...

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