Backbone phosphate groups

Organism Substituent of backbone phosphate group at C-4 C-l Reference... 

In contrast to the backbone structure which represents a constant portion of lipid A the phosphate groups with their various substituents comprise a variable region of lipid A. This natural, obviously restricted interbacterial diversity of phosphate substituents demonstrates that lipid A s of different origin are distinct in their fine structure. In some cases (like Salmonella and Escherichia) the substitution of the backbone phosphate group is not quantitative. This implies a certain heterogeneity of a given lipopolysaccharide preparation expressed on the level of its lipid A component. 

Figure 6 Neutral charge group constructed from backbone phosphate group and mobile counterion. The geometric center of the group is shown along with the switching region. The radii of atoms in the phosphate group are reduced in size for clarity. This arrangement shows the counterion at 6 A from the P.

Generally PNAs have modified polymer backbones (phosphate groups and sugar moieties) and/or modified nucleic acid bases. These analogues can be classified by their preparation methods ... 

Polymerization of nucleotides occurs through the sugar and phosphate groups so that the polymers consist of a sugar-phosphate backbone having pendent bases. 

Figure 8.16 Nonspecific protein-DNA interactions are frequently formed by hydrogen bonds (red) between backbone phosphate oxygen atoms of DNA and main-chain NH groups of the protein.

A nucleic acid polymer contains nucleotide chains in which the phosphate group of one nucleotide links to the sugar ring of a second. The resulting backbone is an alternating sequence of sugars and phosphates, as shown in... 

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