Nucleic acid polymer linkages

Phosphate Esters. An ester is formed by elimination of H20 and formation of a linkage between an acid and an alcohol (or phenol) (Fig. III-22). Phosphomonoesters, especially of monosaccharides, are very common (Fig. ffl-23). Because phosphoric acid is a tribasic acid, it can also form di- and triesters (Fig. III-24). Phosphotriesters are rarely found in nature, but diesters are extremely important, particularly as the fundamental linkage of the nucleic acid polymers, which are sequences of ri-bose (or deoxyribose) units linked by 3 —> 5 phos-phodiester bonds (see Fig. III-25). Like phosphoric acid, which has three dissociable protons (Fig. III-26), phosphomono- and phosphodiesters are acidic and typically ionize as shown in Fig. HI-27. Note the similarities between the pvalues for... 

The subunits of nucleotides are finked together to form a long polymer chain in nucleic acids. The linkages are formed between the phosphate group of one subunit and the sugar group of the next. This matrix forms a sugar-phosphate backbone to the molecule of nucleic acid. 

Fig. 2 Masked endosomolytic agents for pH-triggered endosomal escape. The polymers designed by Meyer et al. [69] (a) and Rozema et al. [71] (b) contain endosomolytic compounds whose lytic potential is activated by endosomal cleavage of masking groups coupled by acid-sensitive linkages. Furthermore, disulfide bonds are embedded which release the nucleic acid after endosomal escape by cleavage in the reducing cytosolic environment...

Poly(vinyl alcohols) bonded with nucleic acid bases through phosphate linkages were prepared. Contents of uracil, thymine and hypoxanthine in the polymers were about 50 to 60 mol-%, and that of adenine was about 10%. Interactions of these polymers with DNA in aqueous solution were studied. The apparent hypochromidty was 6.5% for adenine substituted poly(vinyl alcohol) - DNA and 3% for the corresponding uracil substituted derivative83. ... 

Certain small molecules (monomers) in the cellular soup can be joined to form polymers through repetition of a single type of chemical-linkage reaction (see Figure 2-11). Cells produce three types of large polymers, commonly called macromolecules polysaccharides, proteins, and nucleic acids. Sugars, for example, are the monomers used to form... 

A nucleotide consists of a nitrogenous base (purine or pyrimidine), a pentose sugar, and one or more phosphate groups. Nucleic acids are polymers of nucleotides, Joined together by phosphodiester linkages between the 5 -hydroxyl group of one pentose and the 3 -hydroxyl group of the next. 

Monomer Structure and Linkage Nucleic acids are polynucleotides, unbranched polymers that consist of mononucleotides, each of which consists of an N-containing base, a sugar, and a phosphate group. The two types of nucleic acid, ribonucleic acid (RNA) and deoxyribonucleic acid (DNA), differ in the sugar portions of their mononucleotides RNA contains ribose, and DNA contains deoxyribose, in which —H substitutes for —OH on the second C of ribose. 

Nucleic acids, both DNA and RNA, are polynucleotides (Fig. 3-36). They are polymers that have nucleotides as their repeating subunits. The nucleotides are joined to one another through phosphodiester bonds between the C-3 of one nucleotide and the C-5 of the next. This linkage is repeated many times to huild up a large structure (chain or strand) that contains hundreds to millions of nucleotides within the single macromolecule. Thus the sugar residues are each decorated hy a nucleohase that is either a purine or a pyrimidine. It is these bases that make up a sequence that codes for a particular cellular outcome, be it a protein or a polynucleotide s structural element such as a rihosome (Chaps. 7 and 8). 

Nucleic acids are polymers of mononucleotides. Each mononucleotide is made up of a base-sugar-phosphate unit. These units are linked to each other by a phosphoric acid ester linkage to form nucleic acids. This form of nitrogen accounts for less than 1% of the total soil nitrogen. 

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