Nucleic acids biosynthesis

Zhao K, Liu M, Burgess RR (2010) Promoter and regulon analysis of nitrogen assimilation factor, reveal altemative strategy for coli MG 1655 flagellar biosynthesis. Nucleic Acids Res 38 1273-1283... 

Cellular Protein Biosynthesis. The process of cellular protein biosynthesis is virtually the same in all organisms. The information which defines the amino acid sequence of a protein is encoded by its corresponding sequence of DNA (the gene). The DNA is composed of two strands of polynucleotides, each comprising some arrangement (sequence) of the four nucleotide building blocks of the nucleic acids adenine (A), thymine (T),... 

It iaterferes with the synthesis of the hyphal walls, the biosynthesis of nucleic acids, and the synthesis of chitin. The iateraction with microtubules has also been described. The sensitivity of a cell seems to depend particularly on the abiUty to form griseofulvin—nucleic acid complexes. Further information concerning griseofulvin is available (21). 

There are approximately 20 common naturally occurring amino acids, hence 20 different R groups that appear as pendents on the polyamide chain. Many other amino acids have been isolated or prepared, each representing a variation in R. The number of isomeric stmctures is myriad. Protein biosynthesis is mediated by other biopolymers, the nucleic acids. 

Nucleic acids are the molecules of the genetic apparatus. They direct protein biosynthesis in the body and are the raw materials of genetic technology (see Genetic engineering). Most often polynucleotides are synthesized microbiologicaHy, or at least enzymatically, but chemical synthesis is possible. 

Woodward s synthesis, 4, 416-419 Chlorophyll b, 4, 382 Chlorophyll c, 4, 382 Chlorophyll d, 4, 382 Chlorophylls, 4, 378 biosynthesis reviews, 1, 99 structure, 4, 370 substituents reactions, 4, 402 Chloroporphyrin e, 4, 404 Chloroprothixene pharmacology, 3, 942 Chloropyramine as antihistamine, 1, 177 Chloropyrifos synthesis, 2, 201 Chloropyrifos-ethyl as insecticide, 2, 516 Chloropyrifos-methyl as insecticide, 2, 516 Chloroquine, 1, 145 adsorption on nucleic acids, 1, 179 as antimalarial, 1, 173, 2, 517 Chloroquine, hydroxy-as antimalarial, 2, 517 Chlorosulfonyl isocyanate cycloaddition reactions... 

A rather limited collection of simple precursor molecules is sufficient to provide for the biosynthesis of virtually any cellular constituent, be it protein, nucleic acid, lipid, or polysaccharide. All of these substances are constructed from appropriate building blocks via the pathways of anabolism. In turn, the building blocks (amino acids, nucleotides, sugars, and fatty acids) can be generated from metabolites in the cell. For example, amino acids can be formed by amination of the corresponding a-keto acid carbon skeletons, and pyruvate can be converted to hexoses for polysaccharide biosynthesis. 

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... 

Nucleic acids have recently attracted the attention of very numerous laboratories. This is because nucleic acids belong to the most important components of living matter, for genetic traits are fixed in them and transmitted through them. Nucleic acids also play the main role during biosynthesis of specific proteins. 

One of the lines of approach of such an investigation is the study of analogs of nucleic acid bases. The objective here is to prepare such analogs as would be incorporated into the nucleic acid molecules on the basis of their similarity to the natural species or as could interfere at some of the steps of nucleic acid biosynthesis. 

The Hofmann elimination reaction is not often used today in the laboratory, but analogous biological eliminations occur frequently, although usually with protonated ammonium ions rather than quaternary ammonium salts. In the biosynthesis of nucleic acids, for instance, a substance called adenylosuccinate... 

The nucleic acids, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), are the chemical carriers of a cell s genetic information. Coded in a cell s DNA is the information that determines the nature of the cell, controls the cell s growth and division, and directs biosynthesis of the enzymes and other proteins required for cellular functions. 

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

Quinone methides have been shown to be important intermediates in chemical synthesis,1 2 in lignin biosynthesis,3 and in the activity of antitumor and antibiotic agents.4 They react with many biologically relevant nucleophiles including alcohols,1 thiols,5-7 nucleic acids,8-10 proteins,6 11 and phosphodiesters.12 The reaction of nucleophiles with ortho- and /iara-quinone methides is pH dependent and can occur via either acid-catalyzed or uncatalyzed pathways.13-17 The electron transfer chemistry that is typical of the related quinones does not appear to play a role in the nucleophilic reactivity of QMs.18... 

As already mentioned, a continual inflow of energy is necessary to maintain the stationary state of a living system. It is mostly chemical energy which is injected into the system, for example by activated amino acids in protein biosynthesis (see Sect. 5.3) or by nucleoside triphosphates in nucleic acid synthesis. Energy flow is always accompanied by entropy production (dS/dt), which is composed of two contributions ... 

An antimetabolite interferes with the normal cellular metabolites. For instance, it can act as an inhibitor of one or more enzymes whose substrates are metabolites. Others are incorporated into macromolecules instead of the metabolites. Development of antimetabolites exhibiting anti-cancer activity met with the greatest success for analogues of metabolites involved in the biosynthesis of nucleic acids and of cofactors containing nitrogenous bases. Compounds such as 5-fluorouracyl and methotrexate are remarkably effective against human cancers, even though they feature host toxicity. 

Since the chemistry of nucleic acids was last discussed in this Series,1 publications on the subject have appeared at an unprecedented rate. Degradation products have been further investigated and their structures are more firmly established. Moreover, studies of the properties of these materials have led to a fuller understanding of the behavior of polynucleotides. Emphasis will be laid on the organic chemistry of nucleic acids, and many physicochemical investigations will not be discussed. The period under review has seen the beginning of an understanding of the biosynthesis of nucleic acids, but space does not allow of a consideration of this aspect of the subject. 

Plant metabolism can be separated into primary pathways that are found in all cells and deal with manipulating a uniform group of basic compounds, and secondary pathways that occur in specialized cells and produce a wide variety of unique compounds. The primary pathways deal with the metabolism of carbohydrates, lipids, proteins, and nucleic acids and act through the many-step reactions of glycolysis, the tricarboxylic acid cycle, the pentose phosphate shunt, and lipid, protein, and nucleic acid biosynthesis. In contrast, the secondary metabolites (e.g., terpenes, alkaloids, phenylpropanoids, lignin, flavonoids, coumarins, and related compounds) are produced by the shikimic, malonic, and mevalonic acid pathways, and the methylerythritol phosphate pathway (Fig. 3.1). This chapter concentrates on the synthesis and metabolism of phenolic compounds and on how the activities of these pathways and the compounds produced affect product quality. 

The Li+-induced inhibition of the production of the HSV virus may be related to its actions upon viral DNA polymerase production and activity. Li+ reduces both the synthesis of DNA polymerase in tissue culture and the activity of DNA polymerase in vitro, each by about 50%. It has been proposed that Li+ reduces the biosynthesis of viral polypeptides and nucleic acids, and hence inhibits viral DNA replication by competition with Mg2+, a cofactor of many enzymes [243]. However, the inhibitory effect of Li+ on HSV replication in tissue culture is not affected by Mg2+ levels. A more likely hypothesis is the alteration of the intracellular K+ levels, possibly modifying levels of the high-energy phosphate compounds by replacement of either Na+ or K+ in Na+/K+-ATPase [244]. In tissue culture, HSV replication has been shown to be affected by the... 

Since only less than 10% of G-6-P is channeled into the pentose phosphate cycle (under physiological conditions this percentage varies depending on the different tissues), the question must be discussed, what is the importance of this shunt. With regard to the resulting compounds Eqs. [(3), (5), (6), (7)] one mole NADPH2 appears twice. Furthermore, pentose phosphates are furnished for biosynthesis of nucleotides, nucleic acids, and fatty acids (D5, D6, DIO, H13, M5). 

This great structural variety, however, complicates the specific biosynthesis of complex oligosaccharides. In general, the formation of each saccharide linkage requires specific enzymes ( one linkage—more than one enzyme ) and thus, in comparison with the enzymic synthesis of proteins and nucleic acids, much more effort is needed. 

Whereas DNA is mostly located in the nucleus of cells in higher organisms (with some also in mitochondria and in plant chloroplasts), RNA comes in three major and distinct forms, each of which plays a crucial role in protein biosynthesis in the cytoplasm. These are, respectively, ribosomal RNA (rRNA), which represents two-thirds of the mass of the ribosome, messenger RNA (mRNA), which encodes the information for the sequence of proteins, and transfer RNAs (tRNAs) which serve as adaptor molecules, allowing the 4-letter code of nucleic acids to be translated into the 20-letter code of proteins. These latter molecules contain a substantial number of modified bases, which are introduced enzymatically. 

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