Nucleoproteins and nucleic acids

An even more striking instance of feedback control is found in the synthesis of UNA (see also Nucleoproteins and Nucleic Acids). As pointed nut in Ihat cnlry. normal UNA is composed of the nucleotides dcoxyguanosiiic. dcoxycytidine. deuxyadenosine. and thymidine, and Ihe amounts of the first and second of these are the same, as are those of the third and fourth. Obviously, close control is required of the amounts of these nucleotides that are synthesized by the cell, if they are to be made in the quantities required for DNA synthesis. Evidence has been found that ihe enzyme carbamoylphosphaie L-aspartate carbamoyl transferase, which... 

NUCLEOPROTEINS AND NUCLEIC ACIDS. Nucleic adds are compounds in which phosphoric acid is combined with carbohydrates and with bases derived from purine and pyrimidine. Nucleoproteins are conjugated proteins consisting of a protein moiety and a nucleic acid. Originally, nucleoproteins were thought to occur only in the nuclei of cells, but it was later established that they are far more widely distributed, being found in cells of all types, animal and plant. They are found in the chromosomes, in the genes, in viruses, and bacteriophages. 

RNA. See Genelics and Gene Science (Classical) Nucleoproteins and Nucleic Acids,... 

A. N. Belozersky (1959a). Nucleoproteins and nucleic acids in plants, and their biological significance (in Russian). InXIV Bakhovskoe Chtenie (Fourteenth Bach s Reading), Izdatelstvo Akademii Nauk SSSR, Moscow, p. 32. 

Nucleoproieins. The prosthetic group of the nucleoproteins is nucleic acid, often linked through salt linkages with protamines or histones. The nucleoproteins are present in the nuclei of all cells. Chromasomes are largely nucleoproteins and some plant viruses and bacteriophages have been shown to be pure nucleoproteins. See also histones. 

Virases are much simpler organisms than bacteria, and they are made from protein substances and nucleic acid. A single nucleoprotein molecule formed from molecules of nucleic acid that are chemically bound to a bulky protein molecule can be considered a simple viral particle. The protein molecule plays the role of a protective membrane. Thus the virus can be schematically described as a nucleic acid insert that is protected by a protein covering. A virus can contain either ribonucleic acid or deoxyribonucleic acid, but it never contains both of them together. The type of nucleic acid is the basis of one of the classifications of viruses. Viruses are obligatory intracellular parasites, which, upon entering a cell (i.e. after being infected) use many biochemical systems of the host cell. 

Gel Electrophoresis. This is becoming a more commonly used procedure for purifying proteins, nucleic acids, nucleoproteins, polysaccharides and carbohydrates. The gels can be electroblotted onto membranes and the modem procedures of identifying, sequencing (proteins and nucleic acids) and amplifying (nucleic acids) on sub-micro scales have made this technique of separation a very important one. (See D.Patel Gel Electrophoresis, J.Wiley-Lis, Inc., 1994). 

Protein and Nucleic Acid Interactions The Nucleoprotein Complex... 

Scheme III. Scheme for separating proteins and nucleic acids from a nucleoprotein complex using reversible modifying reagents of amino groups in the proteins...

A separation of the nucleic acid, polysaccharide and protein fractions of tuberculin was effected by the Tiselius electrophoretic technique, which was developed for large scale work in this field by Seibert and Watson. The polysaccharide was relatively immobile and thus was easily removed from the protein and nucleic acid. At pH 5.0 (or less), the nucleic acid and protein traveled in the electrophoretic tube as a single component. At higher pH values, the two tended to move independently. It was probable that some of the protein and nucleic acid was present as nucleoprotein. 

Although proteins and nucleic acids have well-separated functions in many instances, they also work intimately together in specific complexes containing both nucleic acid and protein. Some nucleoprotein complexes are very stable, some are transitory, and others have an intermediate stability. The protein component may provide a structural support for the nucleic acid, but in many cases, the two types of molecule both contribute directly to the function of the complex. Although cases of enzyme action by pure RNA molecules are rare, RNA molecules often act catalytically in nucleoprotein complexes. The chromosome was the first nucleoprotein complex to be discovered and is discussed first. Ribosomes have been studied intensively for many years and contain most of the RNA in the cell. More recently, nucleoprotein structures such as telomerase, spliceosomes, and signal-recognition particles have illustrated the versatility of nucleoprotein complexes. 

In addition to pure proteins, which are constructed entirely from amino acid units, compounds (conjugated proteins) also exist that contain some non-amino acid residues linked to the protein component. These are usually classified according to the nature of the nonprotein component as chromoproteins (with metals), glycoproteins (with carbohydrates), lipoproteins (with lipids), and nucleoproteins (with nucleic acids). 

Nucleoprotein complexes in biological specimens can frequently be separated into their components by fairly simple methods. In the presence of concentrated phenol and a detergent, for example, a cell homogenate will form two liquid phases. Proteins are denatured and become insoluble in the aqueous phase, while the nucleic acids remain soluble. Alternatively, the separation of protein and nucleic acid components from an aqueous NaCl solution can be effected with chloroform (Chapter 11.4). 

The unit structure of all living things is the cell. Suspended in the nucleus of cells are chromosomes, which consist largely of proteins and nucleic acids. The nucleic acids and proteins are intimately associated in complexes called nucleoproteins. Nucleic... 

Low-angle neutron scattering A set of techniques that can be used to find the size of a particle in solution or to find the size or spacing of internal regions that can be distinguished by different neutron scattering power, such as the protein and nucleic acid components of a nucleoprotein particle or labeled proteins within a multisubunit complex. 

In the cell, the histones are associated with DNA and nucleic acid, and the proteins are extracted as a nucleoprotein complex. Deoxyribonucleoproteins contain histones and small amounts of nonbasic protein and lipids as well. The cationic groups of the histones most likely neutralize the phosphate groups of the DNA, but there is some evidence that the chromosomes contain DNA molecules not coated by histones. 

There has been a steady accumulation of evidence to support the Idea that the most Important damage to a cell that leads to mitotic failure Is a macromolecular lesion of DMA in the nucleoprotein system.Cellular radlosensltlvlty In 120 diverse organisms ranging from viruses to higher plants and animals was a direct function of the chromosome volume and nucleic acid content. In the Intact cell of bacteria, protection by thiols appears to be protection of a functional repair mechanism rather than prevention of DNA degradation, but the need for more information about damage to DMA remains moot. 

Nucleoproteins consist of basic proteins in saltlike linkages with nucleic acids (Chapter VIII). Because nucleoproteins are probably present in all cells and vital to growth, there is tremendous biological interest in the histochemical detection of the nucleic acids. Chromosomes, sperm heads, and certain viruses consist largely of nucleoprotein. Two nucleic acid types occur in plant and animal cells deoxyribonucleic acid (DNA), typically present in the nucleus, and ribonucleic acid (RNA), typically found in the cytoplasm and in the nucleolus (see, however. Chapter VIII). Both contain phosphoric acid groups and purine and pyrimidine bases but differ in the pentose moieties. 

Causes, Gout is caused by a defect in the body s natural process of breaking down purines (nucleoproteins, which are compounds of one or more proteins and nucleic acid). This results in the production of too much uric acid, which accumulates in the blood, where it combines with sodium to produce sodium urate. Crystals of uric acid are deposited in tissues around the joints. These deposits cause sudden attacks of swelling, most commonly in the feet. 

Nucleoproteins Combination of proteins and nucleic acids. Present in germs of seeds and glandular tissue... 

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