Nucleic acids, DNA and RNA

Note the loss of oxygen, hence the name de-oxyribose 

A detailed study of DNA and RNA is outside the scope of this book, but the discovery of the exact structural arrangement was first worked out by Crick, Watson, 

Wilkins and Rosalind Franklin. The discovery of the structure of DNA makes fascinating reading. The special issue of New Scientist of 15 March 2003 to mark the 50 years since the discovery of the structure of DNA contains many interesting details.1 

Did you know that if you extracted all the DNA from your cells and put them end to end, they would stretch to the sun and back 600 times This is because we have approximately 10 trillion cells in our body and each cell contains thousands of DNA molecules. These cell molecules are under constant chemical and environmental attack and so there is a similar number of repair events to restore these structures. There are approximately 1020 harmful attacks on the cells of our bodies each day from chemicals, oxidizing free radicals, uv light, cigarette smoke, etc. Unless repair is done quickly, these cells can form deformed structures and cause many molecular-based diseases, including cancers. This is why a constant supply of food in a balanced diet is essential for healthy living. Snack food and slimming diets sometimes lack essential proteins and minerals. 

Two scientists working in Baltimore discovered what they called the master protein, HIF , which controlled the growth of new blood and oxygen levels in the red blood cells, so essential for curing tumours, cancers and helping recovery after heart attacks.2 

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This enzyme interconverts ribulose-5-P and ribose-5-P via an enediol intermediate (Figure 23.30). The reaction (and mechanism) is quite similar to the phosphoglucoisomerase reaction of glycolysis, which interconverts glucose-6-P and fructose-6-P. The ribose-5-P produced in this reaction is utilized in the biosynthesis of coenzymes (including N/ DH, N/ DPH, F/ D, and Big), nucleotides, and nucleic acids (DNA and RNA). The net reaction for the first four steps of the pentose phosphate pathway is... 

This series in heterocychc chemistry is being introduced to collectively make available critically and comprehensively reviewed hterature scattered in various journals as papers and review articles. All sorts of heterocyclic compounds originating from synthesis, natural products, marine products, insects, etc. will be covered. Several heterocyclic compounds play a significant role in maintaining life. Blood constituents hemoglobin and purines, as well as pyrimidines, are constituents of nucleic acid (DNA and RNA). Several amino acids, carbohydrates, vitamins, alkaloids, antibiotics, etc. are also heterocyclic compounds that are essential for life. Heterocyclic compounds are widely used in clinical practice as drugs, but all applications of heterocyclic medicines can not be discussed in detail. In addition to such applications, heterocyclic compounds also find several applications in the plastics industry, in photography as sensitizers and developers, and the in dye industry as dyes, etc. 

Nucleic acids, DNA and RNA, are attractive biopolymers that can be used for biomedical applications [175,176], nanostructure fabrication [177,178], computing [179,180], and materials for electron-conduction [181,182]. Immobilization of DNA and RNA in well-defined nanostructures would be one of the most unique subjects in current nanotechnology. Unfortunately, a silica surface cannot usually adsorb duplex DNA in aqueous solution due to the electrostatic repulsion between the silica surface and polyanionic DNA. However, Fujiwara et al. recently found that duplex DNA in protonated phosphoric acid form can adsorb on mesoporous silicates, even in low-salt aqueous solution [183]. The DNA adsorption behavior depended much on the pore size of the mesoporous silica. Plausible models of DNA accommodation in mesopore silica channels are depicted in Figure 4.20. Inclusion of duplex DNA in mesoporous silicates with larger pores, around 3.8 nm diameter, would be accompanied by the formation of four water monolayers on the silica surface of the mesoporous inner channel (Figure 4.20A), where sufficient quantities of Si—OH groups remained after solvent extraction of the template (not by calcination). 

Those nucleosides found in the nucleic acids DNA and RNA involve the joining of ribose of deoxyribose to a purine or a pyrimidine base. One such nucleoside is adenosine, in which a nitrogen of adenine is linked to carbon 1 of the pentose, ribose. In this form it is a component of RNA but as a phosphory-lated derivative of adenosine (e.g. ATP), which is a high energy compound, it fulfils an important role in metabolism. The dinucleotides NAD and NADP are two cofactors necessary for many enzymic transformations and these also contain /V-glycosides of ribose phosphate. Other important nucleosides are found... 

Through van der Waals and hydrophobic interactions, CNTs were functionalised and made water soluble by the strong adsorption of phospholipids (PLs) grafted onto amino-terminated polyethylene glycol (PEG). The group of Dai bound nucleic acids (DNA and RNA) and proteins to CNTs for specific detection of antibodies (Chen et al., 2003 Kam et al., 2005a, b Liu et al., 2007b). 

Nucleic acids (DNA and RNA) are assembled liom nucleotides, which consist of three components a nitrogenous base, a five-carbon sugar (pentose), and phosphate. 

The nucleic acids DNA and RNA feature diesters of phosphoric acid... 

Whilst many biochemicals are mono-esters of phosphoric acid, the nucleic acids DNA and RNA (see Section 14.2) provide us with good examples of diesters. A short portion of one strand of a DNA molecule is shown here the most significant difference in RNA is the use of ribose rather than deoxyribose as the sugar unit. 

In relation to cancer, there is some evidence that highly oxidized and heated fats may have carcinogenic characteristics. HNE (4-hydroxy-2-frans-nonenal), a secondary lipid peroxidation product derived from linoleic acid oxidation, has assumed particular interest because it has shown cytotoxic and mutagenic properties. Its toxicity, as well other secondary lipid peroxidation products (HHE 4-hydroxy-2-frans-hexenal and HOE 4-h yd roxy-2-trans-oc ten al), is explained through the high reactivity with proteins, nucleic acids, DNA, and RNA. Research links them to different diseases such as atherosclerosis, Alzheimer s, and liver diseases (Seppanen and Csallany, 2006). Research is rapidly progressing, but results are still not conclusive. 

Nucleotides serve as the building blocks for synthesis of the nucleic acids DNA and RNA. 

Nucleic acids DNA and RNA DNA carries the hereditary information, while RNA carries this information from the cell nucleus to the sites of protein synthesis. 

Pyrimidine is a six-membered aromatic heterocyclic compound that contains two nitrogen atoms, separated by a carbon atom, in the ring. Nucleic acids, DNA and RNA, contain substituted purines and pyrimidines. Cytosine, uracil, thymine and alloxan are just a few of the biologically significant modified pyrimidine compounds, the first three being the components of the nucleic acids. 

Purine contains a pyrimidine ring fused with an imidazole nucleus. Guanine and adenine are two purine bases that are found in nucleic acids, DNA and RNA. 

The diazines (pyridazine, pyrimidine, and pyrazine) are six-membered aromatic heterocycles that have two nitrogens in the ring. Cytosine, thymine, and uracil are derivatives of pyrimidine that are important bases in nucleic acids (DNA and RNA). Heterocyclic analogs of the aromatic hydrocarbon naphthalene include pteridines, which have four nitrogens in the rings. Naturally occurring pteridine derivatives include xanthopterin (a pigment) and folic acid (a vitamin). Methotrexate is a pteridine used in cancer chemotherapy. 

The purines are an important class of heterocycles in which an imidazole ring is fused to a pyrimidine ring. Uric acid (the main product of nitrogen metabolism in birds and reptiles), caffeine (present in coffee), and adenine and guanine (nitrogen bases present in the nucleic acids DNA and RNA) are examples of naturally occurring purines. 

The nucleic acids, DNA and RNA, store genetic information in living organisms and are responsible for translating this information into the structure of proteins. Because their structure and function are discussed in great detail in modem biochemistry texts, this chapter concentrates on the organic chemical aspects of these important biomolecules. 

The chapter begins with a discussion of the structure of nucleosides and nucleotides. Then the structure of the nucleic acids, DNA and RNA. the polymers formed from nucleotide monomers, is presented. The function of these polymers in the replication, transcription, and translation of genetic information is briefly addressed. Next, the organic chemistry involved in determining the sequence of DNA is presented. Finally, the synthesis of small DNA molecules in the laboratory is discussed. 

Organic phosphates may be divided into 2 classes basic and weakly basic phosphates. The first class is monosubstituted with pK between 6-7. It possesses the formula R-OPO2- and is present as the terminus phosphate in nucleoside mono-, di-, and triphosphates. The weak phosphates are disubsti-tuted and show the formula R-0(R,-0)P02, pfC<2 and occur as the inside phosphates in nucleoside di- and triphosphates and in nucleic acids DNA and RNA [16-18, 24, 25],... 

Examination of the genealogical mimicry involved in the construction and synthesis of Starburst/cascade dendrimers places this activity at the interface between chemistry and biology. Essentially all genealogical phenomena in biological systems involve and evolve around two generic classes of compositions, namely (a) nucleic acids and (b) proteins. The nucleic acids, DNA and RNA are estimated to be over three billion years old by radioactive carbon dating (see Ref. 206) (see Fig. 45). 

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