Nucleic acid components purines

Jeffrey GA (1989) Hydrogen bonding in crystal structures of nucleic acid components purines, pyrimidines, nucleosides and nucleotides. In Saenger W (ed), Landolt-BOrnstein. Numerical Data and Functional Relationships in Science and Technology. New Series, Group VII, Vol. Ib. Springer, Berlin, pp 277-348... 

Among nucleic acid components purine and pyrimidine bases are electroactive deoxyribose and ribose in nucleosides and nucleotides as well as phosphate groups are inactive at most types of electrodes. 

The 8-aza analogs of purine bases were the first to be studied among all the aza analogs of nucleic acid bases (as early as 1945). Before that time the chemistry of these substances had not been treated in detail from any aspect. Thus the entire chemistry of the u-triazolo [4,5-d]pyrimidines was developed only in connection with the study of antimetabolites of nucleic acid components. Therefore all the papers involved are largely of preparative character and only rarely discuss. theoretical points. 

The major intermediates in the biosynthesis of nucleic acid components are the mononucleotides uridine monophosphate (UMP) in the pyrimidine series and inosine monophosphate (IMP, base hypoxanthine) in the purines. The synthetic pathways for pyrimidines and purines are fundamentally different. For the pyrimidines, the pyrimidine ring is first constructed and then linked to ribose 5 -phosphate to form a nucleotide. By contrast, synthesis of the purines starts directly from ribose 5 -phosphate. The ring is then built up step by step on this carrier molecule. 

Guanine is a preferential DNA target to several oxidants it shows the lowest ionization potential among the different purine and pyrimidine nucleobases and it is the only nucleic acid component that exhibits significant reactivity toward singlet oxygen ( O2) at neutral pH. ... 

Remarkably, HCN-polymers are efficiently obtained at low temperatures suggesting a plausible cold origin-of-life scenario [63-65]. This latter hypothesis provides a mechanism to account for the concentration of HCN and a more stable environment for the newly formed nucleic acid components. Moreover, HCN is easily concentrated at its eutectic temperature (- 23.4 °C) [66,67] and the production of DAMN was found to be accelerated by lowering the temperature of the reaction medium. A large panel of purine derivatives, adenine 1, hypoxanthine 2, diaminopurine 3, xanthine 4 and guanine 5 was obtained after acidic and alkaline hydrolysis at high temperatures of the HCN-polymer produced in a frozen ammonium cyanide solution at - 78 °C for 27 years (Scheme 6 yields of products are reported... 

Frey MN, Koetzle TF, Lehmann MS, Hamilton WC (1973) Predsion neutron diffraction structure determination of protein and nucleic acid components. XII. A study of hydrogen bonding in the purine-pyrimidine base pair 9-methyladenine and 1-methylthymine. J Chem Phys 59 915-924... 

In addition to major nucleosides and bases, modified nucleosides and bases have also been isolated from tRNA hydrolysates and in physiological fluids of man. Unlike the major nucleic acid components, the methylated or otherwise structurally altered purine and pyrimidine compounds are not recycled in the salvage pathways but are excreted. It has been suggested that the measurement of these modified compounds may provide an indicator of the rate of tRNA metabolism. Furthermore, the altered patterns of excretion for these compounds may be used as biomarkers for the detection of disease states and aberrations in metabolic pathways. 

Purine and pyrimidine analogues of nucleic acid components 84MI5. Pyrimidine antibiotics, polyoxines 79H(13)333. 

As a last example of shape of electrostatic potential, we report here some results for a purinic compound, adenine (XXII). Analogous results for other nucleic acid components, thymine and cytosine, may be found in the source paper29). 

Since the reviews by Tipson < > and Barker < > on the chemistry of the nucleic acids, two Chapters have appeared in these Volumes on the chemistry of nucleic acid components, namely, the pyrimidine and purine ... 

Davidson, The Biochemistry of Nucleic Acids (Academic Press, New York. 7th ed., 1972) pp 6-28. Description of DNA components see Nucleic Acids. The purine and... 

Table 1 Abilities of (A) nucleic acid components and (B) some other purine and pyrimidine derivatives to form sparingly soluble compounds with the electrode mercury ...

N.a. are polymers with Af, between 20,000 and about 10 . They contain three structural components the purine and pyrimidine bases, a pentose (either d-ribose in RNA or 2-deoxy-D-ribose in DNA) and es-terified phosphate. The five major bases are uracil (RNA only), thymine (DNA only), adenine, guanine and cytosine (RNA and DNA) in addition, there are over Rare nucleic acid components (see) which occur in various N.a. These rare components are formed by modification of existing structures within the N.a., e.g. by methylation, hydrogenation or rearrangement of normal bases. 

Polynucleotide thioHransferases thiolases catalysing the specific thiolation of purine and pyrimidine bases in the synthesis of Rare nucleic acid components (see). 

Fortunately, my graduate research in biochemistry at Baylor College of Medicine, in Houston, involved studies on the mechanism of formic acid oxidation in animal tissues and on the incorporation of this one-carbon compound into nucleic acid components and their precursors. This provided me with experience in the use of isotopic tracers and the background in biochemical research which proved crucial, in later years, for unraveUng the intermediates and mechanisms of synthesis of purines and other compounds, when I discovered the prebiotic synthesis of adenine and other building blocks of nucleic acids, and a general pathway or method for the prebiotic formation of oligodeoxynucleotides and peptides. 

Purine Nucleic acid component adenine (6-aminopurine) guanine (2-amino-6-hydroxypurine)... 

The most important derivatives of pyrimidines and purines are nucleosides Nucleosides are N glycosides m which a pyrimidine or purine nitrogen is bonded to the anomeric carbon of a carbohydrate The nucleosides listed m Table 28 2 are the mam building blocks of nucleic acids In RNA the carbohydrate component is d ribofuranose m DNA It IS 2 deoxy d ribofuranose... 

Table 28 2 doesn t include all of the nucleoside components of nucleic acids The presence of methyl groups on pyrimidine and purine rings is a common and often important variation on the general theme... 

As is well-known, nucleic acids consist of a polymeric chain of monotonously reiterating molecules of phosphoric acid and a sugar. In ribonucleic acid, the sugar component is represented by n-ribose, in deoxyribonucleic acid by D-2-deoxyribose. To this chain pyrimidine and purine derivatives are bound at the sugar moieties, these derivatives being conventionally, even if inaccurately, termed as pyrimidine and purine bases. The bases in question are uracil (in ribonucleic acids) or thymine (in deoxyribonucleic acids), cytosine, adenine, guanine, in some cases 5-methylcytosine and 5-hydroxymethylcyto-sine. In addition to these, a number of the so-called odd bases occurring in small amounts in some ribonucleic acid fractions have been isolated. 

Purines — These molecules have basic skeletons of purine heterocycles. Adenine and guanine, intrinsic components of nucleic acids, are also ubiquitous molecules. Related molecules are isoguanine, xanthine, and uric acid. 

Only a few years after the Miller-Urey experiment was published, J. Oro was able to synthesize one of the most important biomolecules, adenine. This purine derivative is not only a component of the nucleic acids, but as ATP, adenosine triphosphate (in combination with ribose and three phosphate residues), it plays a key role in the metabolism of all living creatures. The chemical formula of adenine is C5H5N5, or expressed in another way, (HCN)s. 

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