Purines. Pyrimidines and Nucleic Acids

It is clear that further reaction of the hydrocarbons produced in reaction (3) will produce a more complicated series of aldehydes and nitriles via reactions (1) and (2). In the presence of liquid water, a still more complicated reaction sequence becomes possible. Because of the limitations of space, I shall confine the discussion to the possible production of the components of proteins and nucleic acids. The principle pathways of interest here are the synthesis of carbohydrates from formaldehyde and the formation of amino acids, purines and pyrimidines by reactions involving aqueous solutions of HCN. [Although there have been suggestions that HCN can undergo direct polymerization in the gas phase (Matthews and Moser, 1966 Matthews et al., 1977), this reaction has never been directly observed.]... 

Hotchkiss (1949) found that suspensions of Staph, aureus incubated with mixtures of amino acids, purines, and pyrimidines in the presence of penicillin took up more uracil than in the absence of penicillin. It is possible that there is a connection between these various investigations. Since there is no obvious alteration in the uracil content of the staphylococcal nucleic acid formed in the presence of penicillin (Gale and Folkes, 1953a Park, private communication) it seems that the formation of the uridine-5 -pyrophosphate derivatives may represent a stimulation of a side reaction rather than a side-tracking of the incorporation of uracil into nucleic acid. On the other hand, should the incorporation of an essential base into nucleic acid be inhibited, it is probable that the whole nucleic acid synthesis would cease rather than that the relative proportions of the bases within the nucleic acid should change. The true answer must probably await the development of a method for the study of nucleic acid synthesis in detail. George and Pandalai (1948) have claimed that the action of penicillin can be reversed by the addition of nucleic acid to cultures. 

Nucleic acids are acidic substances present m the nuclei of cells and were known long before anyone suspected they were the primary substances involved m the storage transmission and processing of genetic information There are two kinds of nucleic acids ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) Both are complicated biopolymers based on three structural units a carbohydrate a phosphate ester linkage between carbohydrates and a heterocyclic aromatic compound The heterocyclic aro matic compounds are referred to as purine and pyrimidine bases We 11 begin with them and follow the structural thread... 

Purine and pyrimidine bases Nucleosides Nucleotides Nucleic acids... 

These relationships are general Hydroxyl substituted purines and pyrimidines exist in their keto forms ammo substituted ones retain structures with an ammo group on the ring The pyrimidine and punne bases m DNA and RNA listed m Table 28 1 follow this general rule Beginning m Section 28 7 we 11 see how critical it is that we know the cor rect tautomeric forms of the nucleic acid bases... 

Thin-layer chromatography of antibiotics, drugs, alkaloids, purines, pyrimidines, nucleic acids, toxins, and vitamins 98AC7R. 

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. 

Small quantities of additional purines and pyrimidines occur in DNA and RNAs. Examples include 5-methyl-cytosine of bacterial and human DNA, 5-hydroxy-methylcytosine of bacterial and viral nucleic acids, and mono- and di-N-methylated adenine and guanine of... 

Human tissues can synthesize purines and pyrimidines from amphibolic intermediates. Ingested nucleic acids and nucleotides, which therefore are dietarily nonessential, are degraded in the intestinal tract to mononucleotides, which may be absorbed or converted to purine and pyrimidine bases. The purine bases are then oxidized to uric acid, which may be absorbed and excreted in the urine. While little or no dietary purine or pyrimidine is incorporated into tissue nucleic acids, injected compounds are incorporated. The incorporation of injected [ H] thymidine into newly synthesized DNA thus is used to measure the rate of DNA synthesis. 

Ingested nucleic acids are degraded to purines and pyrimidines. New purines and pyrimidines are formed from amphibohc intermediates and thus are dietarily nonessential. 

Goordinated regulation of purine and pyrimidine nucleotide biosynthesis ensures their presence in proportions appropriate for nucleic acid biosynthesis and other metabolic needs. 

Daniels M, Hauswirth W (1971) Fluorescence of the purine and pyrimidine bases of the nucleic acids in neutral aqueous solution at 300 K. Science 171 675... 

Not all analogues become active against cancer cells through incorporation into nucleic acid. Some analogues block the synthesis of normal purine and pyrimidine nucleotides for example, 8-azaguanine blocks guanosine monophosphate (GMP) synthesis and 6-mercaptopurine inhibits adenosine monophosphate (AMP) syn-thesis. 

A further unusual feature of the matrix-dependent polycondensation lies in the character of the nucleobases themselves. Purine mononucleotides undergo polycondensation, in good yields, at complementary matrices consisting of pyrimidine polymers. However, the synthesis of pyrimidine oligonucleotides from their mononucleotides at purine matrices is not effective. This important fact means that a pyrimidine-rich matrix leads to a purine-rich nucleic acid, which is itself not suitable to act as a matrix. This phenomenon also occurs when matrices are used which contain both basic species, i.e., purines and pyrimidines. An increase in the amount of purine in a matrix leads to a clear decrease in its effectiveness (Inoue and Orgel, 1983). However, the authors note self-critically that the condensation agent used cannot be considered to be prebiotic in nature. 

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