Phosphodiester bridge

FIGURE 11.17 3 -5 phosphodiester bridges link nucleotides together to form polynucleotide chains. 

The chemical nature of the monomeric deoxynucleo-tide units of DNA—deoxyadenylate, deoxyguanylate, deoxycytidylate, and thymidylate—is described in Chapter 33. These monomeric units of DNA are held in polymeric form by 3 5 -phosphodiester bridges constituting a single strand, as depicted in Figure 35-1. 

Ribonucleic acid (RNA) is a polymer of purine and pyrimidine ribonucleotides finked together by 3, 5 -phosphodiester bridges analogous to those in DNA (Figure 35—6). Although sharing many features with DNA, RNA possesses several specific differences ... 

DNA is a structurally polymorphic macromolecule which, depending on nucleotide sequence and environmental conditions, can adopt a variety of conformations. The double helical structure of DNA (dsDNA) consists of two strands, each of them on the outside of the double helix and formed by alternating phosphate and pentose groups in which phosphodiester bridges provide the covalent continuity. The two chains of the double helix are held... 

Yun et al. have reported a carboxylate- and a phosphodiester-bridged dinuclear magnesium(II) complex with dicarboxylate ligand 52 (56). The reaction of 52 with 2 equivalents of Mg(N03)2 in MeOH gave a carboxylate-bridged complex 53 (see Scheme 12). The Mg-Mg distance... 

Phospholipids General structure of a phospholipid PHOSPHOLIPIDS (p. 199) Phospholipids are polar, ionic compounds composed of an alcohol (for example, choline, ethanolamine, serine, and glycerol) attached by a phosphodiester bridge to either diacyl-glycerol or to sphingosine. 

The chain-elongation reaction catalyzed by DNA polymerases is a nucleophilic attack by the 3 -hydroxyl group of the primer on the innermost phosphorus atom of the deoxynucleoside triphosphate (Figure 5.22). A phosphodiester bridge forms with the concomitant release of pyrophosphate. The subsequent hydrolysis of pyrophosphate by pyrophosphatase,... 

Figure 5.22. DNA Replication. The formation of a phosphodiester bridge is catalyzed by DNA polymerases.

L)-a-Lyxopyranosyl-(4 3 ) oligonucleotides (47) contain a shortened, 5-bond backbone, but are capable of cross-pairing with both DNA and RNA. The (D)-p-ribopyranosyl-(4 3 ) oligonucleotides (48), however, do not show base pairing under these conditions. The authors conclude that shorter backbones may be tolerated if their vicinal bound phosphodiester bridges can assume... 

A. linked by hydrogen bonding through phosphodiester bridges between the 3 position of one mononucleotide and the 5 position of the next... 

A. The nucleotides in RNA are linked by 3-5 phosphodiester bridges while those in DNA involve 2 -5 bridges. 

Polynucleotides consist of nucleosides joined by 3, 5 -phosphodiester bridges. The genetic message resides in the sequence of bases along the polynucleotide chain. 

Figure 4.22 Chain elongation reaction. DNA polymerases catalyze the formation of a phosphodiester bridge.

Heparin, a glycosaminoglycan is highly anionic. Its negative charges, like the phosphodiester bridges of DNA templates, allow it to bind to lysine and arginine residues of RNA polymerase. 

Scheme 13.25 shows the detail of the extremity of the molecule attached to the cell wall. The covalently linked glycerolipid is, in fact, part of the membrane. The glucosamine is linked to glyceride via a molecule of myoinositol and a phosphodiester bridge. 

Scheme 13.26 gives the detail of the anchoring system to the protein. A phosphodiester bridge links the mannose to an ethanolamine molecule. The carboxylic end of the protein is attached to ethanolamine by an amide bond. 

GIPC-derived oligosaccharides from S. schenckii were liberated by ammonolysis and analyzed by methylation analysis and NMR. The position on the inositol to which the phosphorylceramide group is attached was deduced by a combination of methylation and periodate oxidation studies. The ceramide moiety was linked to position 1 via a phosphodiester bridge. The oligosaccharide structures are shown in Table 2. 

Two types of glycosphingolipids containing phosphodiester bonds are known (i) those containing a 2-aminoethyl phosphate residue csterified to a monosaccharide residue, and (ii) those with a phosphodiester bridge between an inositol residue and the ceramidc moiety. 

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