Ribonucleic acid metabolism

Jacobsen, J. V. Regulation of ribonucleic acid metabolism by plant hormones. Ann. Rev. Plant Physiol., 1977, 28, 537-564. 

Ho, D. T. Varner, J. E. Hormonal control of messenger ribonucleic acid metabolism in barleg aleurone layers. 

Ponce-Castaneda, M.V., Lopez-Casillas, F., Kim, K-H. 1991. Acetyl-coenzyme A carboxylase messenger ribonucleic acid metabolism in liver, adipose tissues, and mammary glands during pregnancy and lactation. J. Dairy Sci. 74, 4013 4021. 

Penman, S. Ribonucleic acid metabolism in mammalian cells. N. Engl. 

Reaction of Deoxyribonuclease. DNAase -acts on polymers of various lengths and forms a mixture of oligonucleotides with very little mononucleotide. Dinucleotides containing purines, pyrimidines, and both have been isolated from digests. The substrate specificity is obviously not so restricted as that of pancreatic RNAase, but has yet to be defined completely. The mechanism of action is also obscure. The linkage of phosphate to the 3 position is split by pancreatic DNAase the monoesters found in the products are all 5 -phosphates. From analogy with ribonucleic acid metabolism, it may be anticipated that DNAase with different specificities will be found, and that some will be found to split the 5 ester bonds. 

The primary defect in pernicious anemia appears to be lack of intrinsic factor in the gastric juice, with the consequent ineffectiveness of ingested vitamin B12. Oral treatment with vitamin B12 must include some source of intrinsic factor. Vitamin B12 has something to do with maturation of blood cells, possibly through some influence upon ribonucleic acid metabolism, and with the metabolism of nerve tissue. 

Glisin, V. R., and Glisin, M. V. (1964). Ribonucleic acid metabolism following, fertilization in sea urchin eggs. Proc. Natl. Acad. Sci. 52, 1548-1553. 

Deoxyribonucleic acid (DNA) serves as a template for the synthesis of nucleic acids. Ribonucleic acid (RNA) executes protein synthesis and thus permits cell growth. Synthesis of new DNA is a prerequisite for cell division. Substances that inhibit reading of genetic information at the DNA template damage the regulatory center of cell metabolism. The substances listed below are useful as antibacterial drugs because they do not affect human cells. 

Enzymes are biological catalysts—i. e substances of biological origin that accelerate chemical reactions (see p. 24). The orderly course of metabolic processes is only possible because each cell is equipped with its own genetically determined set of enzymes. It is only this that allows coordinated sequences of reactions (metabolic pathways see p. 112). Enzymes are also involved in many regulatory mechanisms that allow the metabolism to adapt to changing conditions (see p.ll4). Almost all enzymes are proteins. However, there are also catalytically active ribonucleic acids, the ribozymes" (see pp. 246, 252). 

Fig. 3. Metabolism of the fluoropyrimidines dTMP = deoxythymidine monophosphate, dUMP = deoxyuridine monophosphate, FdUDP = fluorodeoxyuridine diphosphate, FdUMP - fluoro-deoxyuridine monophosphate, FdUTP = fluorodeoxyuridine triphosphate, FU-DNA= fluorouracil-deoxyribonucleic acid, FUDP = fluorouracil diphosphate, FUMP = fluorouracil monophosphate, FU-RNA = fluorouracil-ribonucleic acid, FUTP = fluorouracil triphosphate.

Interferon-a2 concentrated solution is a solution of a protein that is produced according to the information coded by the o2 sub-species of interferon-a gene and that exerts non-specific antiviral activity, at least in homologous cells, through cellular metabolic processes involving synthesis of both ribonucleic acid and protein. Interferon-a2 concentrated solution also exerts antiproliferative activity. Different types of interferon a2, varying in the amino acid residue at position 23, are designated by a letter in lower case. 

Selenocysteine was identified in 1976 (57) in a protein produced by Clostridium stricklandii, and it is thought to be the form in which selenium is incorporated, stoichiometrically, into proteins. Studies with rats show that over 80% of the dietary selenium given them is incorporated into proteins, thus selenocysteine takes on metabolic importance. Selenoproteins having known enzymatic activities contain selenocysteine at the active sites. Two other forms of metabolic selenium are recognized methylated selenium compounds are synthesized for excretion, and selenium is incorporated into some transfer ribonucleic acids (tRNAs) in cultured cells (58). Some of the more important seleno-compounds are listed in Table 4. Examples of simple ring compounds are shown in Figure 4. 

Eizirik, D. L., Welsh, M., Stranded, E., Welsh, N., and Sandler, S. (1990). Interleukin-1 8 depletes insulin messenger ribonucleic acid and increases the heat shock protein hsp 70 in mouse pancreatic islets without impairing the glucose metabolism. Eruiocri-nology (Baltimore) 127, 1190-1191. 

In DNA and the related single-stranded RNA (ribonucleic acid), the phosphate units are monomeric and play a strictly structural role. Phosphates, however, are also essential to the metabolism of living cells, in which formation and subsequent hydrolysis of phosphate-phosphate bonds... 

Nucleotides have a variety of roles in cellular metabolism. They are the energy currency in metabolic transactions, the essential chemical links in the response of cells to hormones and other extracellular stimuli, and the structural components of an array of enzyme cofactors and metabolic intermediates. And, last but certainly not least, they are the constituents of nucleic acids deoxyribonucleic acid (DNA) and ribonucleic acid (ENA), the molecular repositories of genetic information. The structure of every protein, and ultimately of every biomolecule and cellular component, is a product of information programmed into the nucleotide sequence of a cell s nucleic acids. The ability to store and transmit genetic information from one generation to the next is a fundamental condition for life. 

Each one of the thousands of chemical reactions of metabolism is catalyzed by an enzyme. Most of these enzymes are proteins, but others are made from RNA (ribonucleic acid). In both cases enzymes are very large molecules with precise three-dimensional structures. The study of the properties of enzymes and of enzymatic catalysis is a third theme of the book. Not only are the chemical mechanisms by which enzymes act of interest but also enzymes are often targets for useful drugs. Incorrectly formed enzymes can result in serious diseases. 

Calhoun, B. A., J. Overmeyer, and W. Sunderman Jr. Studies of trace metal metabolism Electron paramagnetic resonance of manganese in ribonucleic acids. Proc. Soc. Exptl. Biol. Med. 119, 1089 (1965). 

Nucleotides are stmctural units of deoxyribonucleic acid (DNA), ribonucleic acid (RNA) and cofactors such as coenzyme A (CoA), flavin adenine dinucleotide (FAD), nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), with important roles in energy transfer, metabolism and intracellular signalling. 

A virus is a submicroscopic agent of infectious disease that requires a living cell for its multiplication. The two essential components of a virus are protein and nucleic acid. Whereas normal cells contain both RNA (ribonucleic acid) and DNA (deoxyribonucleic acid), a given virus contains only one, not both. A virus cannot multiply on its own as a normal cell does. It has no metabolic enzymes, uses no nutrients, and produces no energy. It is just a particle of protein and nucleic acid. A viral particle is tightly packed inside a protein coat that protects it. This unit is called a virion. 

Fohc acid is a precursor of several important enzyme cofactors required for the synthesis of nucleic acids (qv) and the metabolism of certain amino acids. Fohc acid deficiency results in an inability to produce deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and certain proteins (qv). Megaloblastic anemia is a common symptom of folate deficiency owing to rapid red blood cell turnover and the high metabolic requirement of hematopoietic tissue. One of the clinical signs of acute folate deficiency includes a red andpainfiil tongue. Vitamin B 2 folate share a common metaboHc pathway, the methionine synthase reaction. Therefore a differential diagnosis is required to measure foHc acid deficiency because both foHc acid and vitamin B 2 deficiency cause... 

There were early reports that in patients with psoriasis there was a greater output of urinary uric acid (Bll) and increases in serum uric acid levels (E2). Eisen and Weissman showed that the increase in uric acid excreted was proportional to the amount of skin involved in the disease. This increase in uric acid may be partially the result of increased turnover of the diseased cells and release of their nucleic acid to the purine catabolic pool. There are other alterations in nucleic acids related to cellular metabolism in psoriasis. The ribonucleic acid concentration of psoriatic tissues is approximately 3 times that of normal skin, and the DNA can be as much as 13-14 times greater than in normal tissues (H8, W5). A fundamental change in the nature of psoriatic deoxyribonucleic acid was suggested by Steigleder et al. (S36), who isolated DNA s from psoriatic skin and from normal skin and... 

Pathophysiology Acetaminophen is metabolized via the cytochrome P450 enzymes into a deleterious product A-acetyl benzoquinoneimine, an unstable intermediate, which causes arylated derivatives of protein, lipid, ribonucleic acid (RNA), and deoxyribonucleic acid (DNA), causing destruction of these compounds. Because the Uver has high levels of cytochrome P450 enzymes, it is the major organ affected by acetaminophen overdose. 

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