Nucleic Acids in Protein Synthesis

FIGURE 3. Simplified scheme for the role of nucleic acids in protein synthesis. 

Dacarbazine is activated by photodecomposition (chemical breakdown caused by radiant energy) and by enzymatic N-demethylation. Formation of a methyl carbonium ion results in methylation of DNA and RNA and inhibition of nucleic acid and protein synthesis. Cells in all phases of the cell cycle are susceptible to dacarbazine. The drug is not appreciably protein bound, and it does not enter the central nervous system. 

It should already be clear from what has been stated that a great diversity of viruses exist. It should therefore not be surprising that there is also a great diversity in the manner by which virus multiplication occurs. Interestingly, many viruses have special features of their nucleic acid and protein synthesis processes that are not found in cells. In the present chapter, we are only able to present some of the major types of virus replication patterns, and must skip some of the interesting exceptional cases. 

We consider, successively, the catalytic role of several classes of mononuclear Zn2+ enzymes and then discuss enzymes with di- and tri-nuclear cocatalytic zinc centres, some of which include a metal ion other than zinc. We conclude with a presentation of some of the zinc-based motifs found in proteins involved in the regulation of nucleic acid and protein synthesis. 

Mycelial growth is more sensitive to cymoxanil than early growth phases, including the release of zoospores from sporangia and their germination. Cymoxanil inhibits nucleic acid and protein synthesis in some fungi but may have to be activated to induce a fungicidal response. 

M. Goodman and F. Morehouse, Organic Molecules in Action, Gordon and Breach, New York, 1973. See, for example, the chapters on prebiotic synthesis, origin of the cell, nucleic acids, and protein synthesis. 

Low activities of orotidine phosphate decarboxylase and (usually) orotate phosphoribosyltransferase are associated with a genetic disease in children that is characterized by abnormal growth, megaloblastic anemia, and the excretion of large amounts of orotate. When affected children are fed a pyrimidine nucleoside, usually uridine, the anemia decreases and the excretion of orotate diminishes. A likely explanation for the improvement is that the ingested uridine is phosphorylated to UMP, which is then converted to other pyrimidine nucleotides so that nucleic acid and protein synthesis can resume. In addition, the increased intracellular concentrations of pyrimidine nucleotides inhibit carbamoyl phosphate synthase, the first enzyme in the. naibwav of aro-tate synthesis. 

Zinc 2-3 g 15 mg > 160 enzymes in main metabolic pathways, nucleic acid and protein synthesis, immune system Occurs in Iran, Egypt TPN, genetic disease, traumatic stress growth depression, delayed sexual maturation, skin lesions, depression of immunocompetence, change of taste acuity Unlikely except from prolonged therapeutic use can interfere with Fe and Cu metabolism... 

Mechanism of Action. Pyrimethamine blocks the production of folic acid in susceptible protozoa by inhibiting the function of the dihydrofolate reductase enzyme. Folic acid helps catalyze the production of nucleic and amino acids in these parasites. Therefore, this drug ultimately impairs nucleic acid and protein synthesis by interfering with folic acid production. The action of sulfadoxine and other sulfonamide antibacterial agents was discussed in Chapter 33. These agents also inhibit folic acid synthesis in certain bacterial and protozoal cells. 

Higgins, T. J. V. Zwar, J. A. Jacobsen, J. V. Hormonal control of the level of translatable mRNA for barley aleurone layers. In Nucleic Acids and Protein Synthesis in Plants, Ed. J. H. Well L. Bogorad, Paris ... 

As discussed earlier, there are a number of ways by which an antibiotic can selectively interfere with biochemical processes in a microbe. This part of the chapter deals in more detail with the respective mechanisms. These include the cell wall and membrane, nucleic acid and protein synthesis, and intermediary metabolism. 

The backbone of a nucleic acid is a polymer of ribofuranoside rings (five-membered rings of the sugar ribose) linked by phosphate ester groups. Each ribose unit carries a heterocyclic base that provides part of the information needed to specify a particular amino acid in protein synthesis. Figure 23-21 shows the ribose-phosphate backbone of RNA. 

Anti-viral drugs use mechanisms that interfere with nucleic acid and protein synthesis, inhibiting their attachment to and penetration of host cells. Because the viruses frequently adapt their structures, their elimination is difficult. A research team in Cambridge19 are looking at what they call a mutator protein . This protein is made by our own cells and is released to sneak inside certain viruses and cause chaos and mutations in their genome. Unfortunately the AIDS virus has evolved a defence against this process, but it is useful for other viruses. 

Bernstein, I. A., Relation of the Nucleic Acids to Protein Synthesis in the... 

D is a plant-growth regulator that stimulates nucleic acid and protein synthesis and affects enzyme activity, respiration, and cell division. It is absorbed by plant leaves, stems, and roots and moves throughout the plant. It accumulates in growing tips. 

---