Nucleic acid derivatives

Nucleotides consist of a pentose sugar joined to a nitrogen base (purine or pyrimidine) and phosphate group. Nucleic acids are polymerized from nucleotides and consist of ribonucleic acid (RNA) and deoxyribosenucleic acid (DNA). In DNA, the pentose sugar is D-deoxyribose and the bases are adenine, guanine, thymine, and cytosine the pentose sugar in RNA is o-ribose and the bases are adenine, guanine, thymine, and cytosine. There also are other bases that occur infrequently in both RNA and DNA. 

Most of the cell s DNA is in the nucleus, although DNA is also present in mitochondria and the chloroplasts of plants. In higher animals, nuclear DNA is bound to histones, which are basic proteins. The basic composition of nuclear DNA is characteristic of an organism and is expressed as the percentage of guanine and cytosine (G and C) bases. Base combinations vary in the animal kingdom. For instance, mammals have about 40% G and C, whereas invertebrates have lower values. 

Cells contain more RNA than DNA, and the three types of RNA are ribo-somal (rRNA), transfer (tRNA), and messenger (mRNA). rRNA constitutes about 75% of all the RNA, whereas tRNA accounts for 10-15% of the total and functions to transport amino acids in protein synthesis. mRNA consists of only 5-10% of the total and functions to carry information for protein synthesis from the nucleus to the cytoplasm. 

Nucleotides are the basic building blocks of nucleic acids, whereas nucleosides are nucleotides without the phosphate group (i.e., nucleoside = base + sugar, and nucleotide = base + sugar + phosphate). 

The amount of nucleosides in cells is negligible also deoxyribonucleotides occur at insignificant levels in tissues. Ribonucleotides are important cellular components and occur as 5 -monophosphates, di-, tri-, and cyclic 3, 5 -phos-phates. Nucleoside phosphates function as energy carriers and serve as precursors for the synthesis of nucleic acids. Cyclic nucleotides (i.e., cyclic 3, 5 -AMP and cyclic-3, 5 -GMP) also play a role in metabolic regulation. 

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Synthesis of reactive nucleic acids derivatives and their use for investigations of structure and functions of biopolymers 98UK688. 

In addition to the nucleic acids themselves, nucleic acid derivatives such as ATP are involved as phosphorylating agents in many biochemical pathways, and several important coenzymes, including NAD+, PAD, anti coenzvme A, have nucleic acid components. 

Metal ion interactions with nucleic acids and nucleic acid derivatives. L. G. Marzilli, Prog. Inorg. 

Figure 1.83 Succinic anhydride has been used in nonaqueous conditions to modify the 5 -hydroxyl group of nucleic acid derivatives such as AZT.

Enhancing the overall resistivity of the body is observed upon treatment with a number of known drugs immunostimulants (caffeine, phenamine, methyluracil), vitamins (retinol, ascorbic acid, vitamins of group B), nucleic acid derivatives, and also drugs of natural or genetically engineered origin made specifically for this purpose. 

Nucleic Acid Derivatives, Advances in the Photochemistry of (Burr).. . ... 

The third class of cosubstrates for kinases encompasses substrates that are neither nucleic acid derivatives nor proteins, but are small molecules which serve many functions, often in energy... 

XVI. The Action of Ionizing Radiation on Nucleic Acid Derivatives. . 283... 

A particular dimer of thymine was the first heat-stable photoproduct isolated from photolysis of nucleic acid derivatives, and still appears to be the principal isolable product from photolysis of most examples of biologically active DNA.8,10 Investigation of this product has drawn much attention in recent years. Most of this work has been carried out on polynucleotides and nucleic acids and will be dealt with in those sections. The remaining work has been largely carried out with... 

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