Nucleic acids, carbohydrate constituents

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. 

The phosphoproteins and the nucleoproteins contain also the element phosphorus in the former, probably combined directly with one of the constituents of the protein molecule in the latter, combined with a purine base or a carbohydrate, which substances constitute nucleic acid. 

Proteins with molecular weights in the millions are the major constituents of all living cells. Simple proteins are hydrolyzed only to amino acids. Coqjugated proteins are hydrolyzed to amino acids and nonpeptide substances known as prosthetic groups. These prosthetic groups include nucleic acids of nucieoproteins, carbohydrates of glycoproteins, pigments (such as hemin and chiorophyli) of chromoproteins, and fats or lipids of lipoproteins. 

Fig. 18.3. Raman spectral analysis of foetal osteoblast (FOB) differentiation. Unsupervised PCA of FOB cells cultured for 3 days in bioactive glass (BG) conditioned media (triangle) or control media (circle) (a). BG-treated cells formed a distinct cluster separate from control cells after 3 days culture. Least square (LS) analysis (which decomposes the cell spectra into the linear combination of Raman spectra obtained from the pure chemical constituents of the cell, e.g. nucleic acid, proteins, lipids, phospholipids and carbohydrates) of the relative RNA concentration of FOBs cultured for 1, 3 and 14 days in culture media (black) or BG condition media (grey), revealed a significantly reduced relative RNA concentration in FOBs culture in BG-conditioned media (b). FOBs cultured in BG-conditioned media appeared to accelerate FOB differentiation into mature adult osteoblast phenotypes (parallel gene and protein expression experiments confirmed this). Significant difference to control (p <0.05) [38]...

The term nucleoside was originally proposed by Levene and Jacobs in 1909 for the carbohydrate derivatives of purines (and, later, of pyrimidines) isolated from the alkaline hydrolyzates of yeast nucleic acid. The phosphate esters of nucleosides are the nucleotides, which, in polymerized forms, constitute the nucleic acids of all cells.2 The sugar moieties of nucleosides derived from the nucleic acids have been shown, thus far, to be either D-ribose or 2-deoxy-D-eri/fAro-pentose ( 2-deoxy-D-ribose ). The ribo-nucleosides are constituents of ribonucleic acids, which occur mainly in the cell cytoplasm whereas 2-deoxyribo -nucleosides are components of deoxypentonucleic acids, which are localized in the cell nucleus.3 The nucleic acids are not limited (in occurrence) to cellular components. They have also been found to be important constituents of plant and animal viruses. 

The discovery of a small proportion of a nucleoside containing thymine42 in the ribonucleic acid of two strains of Escherichia coli, in Aerobacter aero-genes, and in commercial, yeast-ribonucleic acid emphasizes the point made previously,26-28 namely, that the nucleic acids may contain constituents other than those heretofore identified. Alkaline hydrolysis of the ribonucleic acid from E. coli gave nucleotides42 (probably the 2- and 3-phosphate esters) which were converted to the nucleoside with prostatic phospho-monoesterase.62 Enzymic hydrolysis of the nucleic acid preparation also led to the nucleoside, which was degraded further to thymine by hydrolysis with perchloric acid.42 There can be little doubt that this carbohydrate derivative of thymine is intimately bound as part of the polynucleotide chain of this particular ribonucleic acid. 

In general, the proportions of the main tissue constituents, proteins, lipids, carbohydrates and nucleic acids (Table 4.2) show a somewhat different... 

Carbonyl compounds are everywhere. In addition to their uses as reagents and solvents, they are constituents of fabrics, flavorings, plastics, and drugs. Naturally occurring carbonyl compounds include proteins, carbohydrates, and nucleic acids that make up all plants and animals. In the next few chapters, we will discuss the properties and reactions of simple carbonyl compounds. Then, in Chapters 23 and 24, we apply this carbonyl chemistry to carbohydrates, nucleic acids, and proteins. 

Three-center hydrogen bonds in the nucleic acid constituents occur as frequently as in the carbohydrates (see Thble 2.3). Because there are virtually no neutron diffraction studies available for this class of compounds, the analysis of the three-center bonds has to rely on data where the X-H bond lengths are normalized and are therefore to some extent less reliable than those of the carbohydrates (Table 8.3) which are based on neutron diffraction data. 

Since nucleic acid constituents exhibit a wider range of donor and acceptor types, the three-center hydrogen bonds have more variation than in+the carbohydrates. It is clear from the data summarized in Thble 8.5 that - NH3 (and NH4), O—H and — NH2 groups tend to form more three-center bonds than OwH... 

The three-center hydrogen bonds observed in the crystal structures of the amino acids are described in Thble 8.6. They range from symmetrical to unsymmet-rical, as found for the carbohydrates and nucleic acid constituents, but there is a significantly greater tendency to form more unsymmetrical bonds. A particular feature are the chelated three-center hydrogen bonds discussed below. 

Carbohydrate is essential for the survival of some tissues and as a structural constituent of nucleic acids, glycoproteins, proteoglycans, and glycolipids. The normal adult can synthesize all the needed carbohydrate from noncarbohydrate sources, namely, amino acids and glycerol. Thus,... 

Occurrence. D-Ribose (9) and 2-deoxy-D-eryf/iro-pentose ( 2-deoxy-D-ribose ) are the carbohydrate constituents of nucleic acids, which are found in all cells. D-Ribose is also a constituent of several coenzymes. In these natural products, the sugar occurs in the (3-furanose form. 

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