Nucleic acids heterocycles

Fig. 1. Watson-Crick base-pairing interactions for common nucleic acid heterocycles.

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... 

Two nitrogen containing heterocyclic aromatic compounds—pyrimidine and purine— are the parents of the bases that constitute a key structural unit of nucleic acids... 

Another property of pyrimidines and purines is their strong absorbance of ultraviolet (UV) light, which is also a consequence of the aromaticity of their heterocyclic ring structures. Figure 11.8 shows characteristic absorption spectra of several of the common bases of nucleic acids—adenine, uracil, cytosine, and guanine—in their nucleotide forms AMP, UMP, CMP, and GMP (see Section 11.4). This property is particularly useful in quantitative and qualitative analysis of nucleotides and nucleic acids. 

Modern concepts have been extended to the chemistry of heterocyclic compounds more slowly than to the chemistry of aromatic and aliphatic systems, but efforts are now being made to classify and explain the properties and reactions of heterocyclic compounds in terms of these newer ideas (cf. reference 11). However, many of the most important heterocyclic compounds are potentially tautomeric, and elucidation of their tautomeric composition must precede a logical treatment of their properties. Further, many natural products such as the nucleic acids and alkaloids contain potentially tautomeric groups and information of this type is needed for a detailed explanation of th reactions which they undergo,... 

Photocleavage of nucleic acids with participation of metal complexes with heterocyclic ligands 98CRV1171. 

Pyrimidine and imidazole rings are particularly important in biological chemistry. Pyrimidine, for instance, is the parent ring system in cytosine, thymine, and uracil, three of the five heterocyclic amine bases found in nucleic acids An aromatic imidazole ring is present in histidine, one of the twenty amino acids found in proteins. 

Just as proteins are biopolymers made of amino acids, nucleic acids are biopolv-mers made of nucleotides joined together to form a long chain. Each nucleotide is composed of a nucleoside bonded to a phosphate group, and each nucleoside is composed of an aldopentose sugar linked through its anomeric carbon to the nitrogen atom of a heterocyclic purine or pyrimidine base. 

Nucleotide (Section 28. ) A nucleic acid constituent, consisting of a sugar residue bonded both to a heterocyclic purine or pyrimidine base and to a phosphoric acid. 

Chapter 28, Biomolecules Nucleic Acids—Coverage of heterocyclic chemistry has been moved to Chapter 24. 

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. 

Taguchi H, Yokoi T, Tsukatani M, Okada Y (1995) Tetrahedron 27 7361 Vekemans J, Pollers-Wieers C, Hoornaert G (1983) J Heterocyclic Chem 20 919 Tutonda M, Vanderzande D, Hendrickx M, Hoornaert G (1990) Tetrahedron 46 5715 Deceuninck JA, Verschave P, Buffel DK, Tutonda M, Hoornaert G (1991) In Townsend LB, Stuart Tipson R (eds) Nucleic acid chemistry, improved and new synthetic procedures, methods and techniques. Wiley, New York, p 144 Buysens KJ, Vandenberghe DM, Toppet SM, Hoornaert GJ (1996) J Chem Soc Perkin Trans 1 231... 

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. 

Maes BUW (2006) Transition-Metal-Based Carbon-Carbon and Carbon-Heteroatom Bond Formation for the Synthesis and Decoration of Heterocycles. 1 155-211 Maiti M, Kumar GS (2007) Protoberberine Alkaloids Physicochemical and Nucleic Acid Binding Properties. lO. 155-210... 

Purine is the parent heterocyclic compound of the methylxanthines, which are often referred to as the purine alkaloids.1-7 Purine is also the parent compound of some of the base constituents of the nucleotides, which in turn are part of the nucleic acids RNA and DNA. Thus, it appears that the purine alkaloids have similar precursors to nucleic acids. 

Acridine and its derivatives are also fused nitrogen heterocycles similar to acridones, which display a high fluorescence quantum yield and possess the ability to intercalate tightly, though reversively, to the DNA helical structure [73], with large binding constants [74]. As a result, acridine dyes are recognized in the field of the development of probes for nucleic acid structure and conformational determination [75-77]. 

Heterocycles are found in a wide variety of natural products, and the chemical nature of these moieties imparts recognition elements critical to both protein and nucleic acid targets. These moieties may be biosynthesized via either ribosomal or nonribosomal pathways and can occur either singly within a molecule or as multiple, repeating heterocyclic units within the same compound (Figure 13.19). 

The analysis of extraterrestrial matter is concentrated on the detection of nucleic acid and protein building blocks, i.e., N-heterocycles and amino acids. The search for such compounds began immediately after the fall of the Murchison meteorite. Twenty-two amino acids were detected in it as early as 1974 eight of them pro-teinogenic, ten which hardly ever occurred in biological material, and four which were unknown in the biosphere. Up to now, about 70 amino acids have been identified (Cronin, 1998), the most common being glycine and a-aminoisobutyric acid. The latter is a branched-chain amino acid with the smallest possible number of carbon atoms. The most frequently found amino acids occur in concentrations of... 

The chemistry of nucleic acid analogs has received much attention in recent years, and a series of nucleic acid models has been designed and widely prepared, in order to estimate and utilize their functionalities in relation to the specific basepairing properties ( J., i, ). These monomers and polymers, particularly those containing purines, pyrimidines, nucleosides, and nucleotides, are not only of interest to the field of heterocyclic organic chemistry, but also to that of biomimetic macro-molecular chemistry as synthetic analogs of the nucleic acids. 

Purines A series of heterocyclic compounds that are variously substituted in nature and are known also as purine bases. They include adenine and guanine, constituents of nucleic acids, as well as many alkaloids such as caffeine and theophylline. Uric add is the metabolic end product of purine metabolism. [NIH]... 

A nucleotide consists of a heterocyclic base linked to a sugar (ribose or deoxyribose) and a phosphate group also linked to the sugar (Figure 10.6). Nucleic acids are polymers of nucleotides linked together by phosphodiester bonds (Figure 10.7). The enzymes that catalyse the breakdown of nucleic acids to nucleotides are nucleases. 

The storage of genetic information and the transcription and translation of this information are functions of the nucleic acids deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). They are polymers whose building blocks are nucleotides, which are themselves combinations of three parts, i.e. a heterocyclic base, a sugar, and phosphate (see Section 14.1). 

The bases are monocyclic pyrimidines (see Box 11.5) or bicyclic purines (see Section 11.9.1), and all are aromatic. The two purine bases are adenine (A) and guanine (G), and the three pyrimidines are cytosine (C), thymine (T) and uracil (U). Uracil is found only in RNA, and thymine is found only in DNA. The other three bases are common to both DNA and RNA. The heterocyclic bases are capable of existing in more than one tautomeric form (see Sections 11.6.2 and 11.9.1). The forms shown here are found to predominate in nucleic acids. Thus, the oxygen substituents are in keto form, and the nitrogen substituents exist as amino groups. 

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