Nucleic acids types

Greiff [3.25] classified the virus into five categories 1, Nucleic acid type (either DNA-core or RNA-core) 2, sensitivity against lipid solvents 3, envelope about the nucleocapsid or not (naked) 4, pH sensitivity, exposure to pH 3 for 30 min differentiates between those viruses, which lose more than a decade in titer and those which lose no titer or less than one decade 5, heat-sensitive virus cannot be exposed to +50 °C for 30 min. 

However, the molecular weight, for example, may vary from 15,000 (hen egg white lysozyme) to 2,000,000 (keyhole limpet hemocyanin) daltons. Protein antigens function as the most potent immunogens, and polysaccharide antigens rank second. For cell-mediated immunity, only proteins serve as immunogens. Certain nucleic acid types such as Z-DNA and other molecules can also stimulate antibody production. 

The synthesis of a number of phosphonate derivatives of methylenecyclo-propane nucleoside analogues (86a-l) has been reported by Zemlicka. Most were obtained by an alkylation-elimination approach. Starting from a meth-anesulfonate, methylenecyclopropane phosphonates were obtained by Michaelis-Becker reaction with alkyl phosphites and converted to vicinal dibromides, subsequently used for alkylation-elimination of nucleic acid type bases. All compounds were evaluated against herpes viruses, hepatitis B and HIV and were found to be inactive except for (86b), which was found to inhibit VZV proliferation. 

An unanswered question does remain regarding the extension of our findings to predict the adsorption characteristics of human hepatitis type A. This virus is the etiologic agent of infectious hepatitis, which is considered to be the most serious problem in the transmission of waterborne virus disease (i). It is similar to other enteroviruses in terms of size (27 nm in diameter), density in CsCl gradients (1.34 g cm ), stability in the presence of chemical and physical agents, and probable nucleic acid type (69). However, electrokinetic properties of this virus have yet to be characterized. This information is required before accurate predictions of electrostatic components of adsorption can be made for this virus. 

The nucleic acids are polymers of a large number of appropriate mononucleotide residues (base-sugar-phosphate) joined by internucleotidic ribose phosphate esterifications the polymeric linkage is the phosphate ester bond. Their biological importance is evident from the fact that two types, called RNA and DNA, are found in all cells and some viruses. Although DNA appears to exist exclusively within the cell nucleus, RNA (though more abundant in the cytoplasm) also occurs to some extent in the nucleus. RNA represents the sole nucleic acid type associated with the plant viruses 156) whereas the bacterial viruses, which are rich in DNA, apparently lack RNA 157). (For histochemical identification, see Chapter XI.)... 

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. 

Taking into account the hydration shell of the NA and the possibility of the water content changing we are forced to consider the water -I- nucleic acid as an open system. In the present study a phenomenological model taking into account the interdependence of hydration and the NA conformation transition processes is offered. In accordance with the algorithm described above we consider two types of the basic processes in the system and thus two time intervals the water adsorption and the conformational transitions of the NA, times of the conformational transitions being much more greater... 

Lipids differ from the other classes of naturally occurring biomolecules (carbohy drates proteins and nucleic acids) in that they are more soluble m nonpolar to weakly polar solvents (diethyl ether hexane dichloromethane) than they are m water They include a variety of structural types a collection of which is introduced m this chapter... 

As the result of high specificity and sensitivity, nucleic acid probes are in direct competition with immunoassay for the analytes of some types of clinical analytes, such as infectious disease testing. Assays are being developed, however, that combine both probe and immunoassay technology. In such hybrid probe—immunoassays, the immunoassay portion detects and amplifies the specific binding of the probe to a nucleic acid. Either the probe per se or probe labeled with a specific compound is detected by the antibody, which in turn is labeled with an enzyme or fluorophore that serves as the basis for detection. 

Vimses are one of the smallest biological entities (except viroids and prions) that carry all the iaformation necessary for thek own reproduction. They are unique, differing from procaryotes and eucaryotes ia that they carry only one type of nucleic acid as genetic material, which can be transported by the vims from one cell to another. Vimses are composed of a shell of proteki enclosing a core of nucleic acid, either ribonucleic acid (RNA) or deoxyribonucleic acid (DNA), that codes for vkal reproduction. The outer shell serves as a protective coat to keep the nucleic acid kitact and safe from enzymatic destmction. In addition to thek proteki coat, some vimses contain an outer covering known as an outer envelope. This outer envelope consists of a Hpid or polysaccharide material. 

Once kiside the host ceU, the vims must repHcate its own nucleic acid. To do this, it often uses part of the normal synthesizing machinery of the host ceU. If the vims is to continue its growth cycle, vkal nucleic acid and vkal proteki must be properly transported within the ceU, assembled kito the kifective vims particle, and ultimately released from the ceU. AH of these fundamental processes kivolve an intimate utilization of both ceUular and vkal enzymes. Certain enzymes that ate kivolved ki this process ate specificaHy suppHed by the invading vims. It is this type of specificity that can provide the best basis for antivkal chemotherapy Thus an effective antivkal agent should specificaHy inhibit the vkal-encoded or vims-kiduced enzymes without inhibition of the normal enzymes involved in the biochemical process of the host ceH. Vims-associated enzymes have been reviewed (2,3) (Table 1). 

Technetium-99m coordination compounds are used very widely as noniavasive imaging tools (35) (see Imaging technology Radioactive tracers). Different coordination species concentrate ia different organs. Several of the [Tc O(chelate)2] types have been used. In fact, the large majority of nuclear medicine scans ia the United States are of technetium-99m complexes. Moreover, chiral transition-metal complexes have been used to probe nucleic acid stmcture (see Nucleic acids). For example, the two chiral isomers of tris(1,10-phenanthroline)mthenium (IT) [24162-09-2] (14) iateract differentiy with DNA. These compounds are enantioselective and provide an addition tool for DNA stmctural iaterpretation (36). 

Factors to be considered in maldng the selection of chromatography processing steps are cost, sample volume, protein concentration and sample viscosity, degree of purity of protein product, presence of nucleic acids, pyrogens, and proteolytic enzymes. Ease with which different types of adsorbents can be washed free from adsorbed contaminants and denatured proteins must also be considered. 

A nucleic acid can never code for a single protein molecule that is big enough to enclose and protect it. Therefore, the protein shell of viruses is built up from many copies of one or a few polypeptide chains. The simplest viruses have just one type of capsid polypeptide chain, which forms either a rod-shaped or a roughly spherical shell around the nucleic acid. The simplest such viruses whose three-dimensional structures are known are plant and insect viruses the rod-shaped tobacco mosaic virus, the spherical satellite tobacco necrosis virus, tomato bushy stunt virus, southern bean mosaic vims. 

In contrast, RNA occurs in multiple copies and various forms (Table 11.2). Cells contain up to eight times as much RNA as DNA. RNA has a number of important biological functions, and on this basis, RNA molecules are categorized into several major types messenger RNA, ribosomal RNA, and transfer RNA. Eukaryotic cells contain an additional type, small nuclear RNA (snRNA). With these basic definitions in mind, let s now briefly consider the chemical and structural nature of DNA and the various RNAs. Chapter 12 elaborates on methods to determine the primary structure of nucleic acids by sequencing methods and discusses the secondary and tertiary structures of DNA and RNA. Part rV, Information Transfer, includes a detailed treatment of the dynamic role of nucleic acids in the molecular biology of the cell. 

H bonding also vitally influences the conformation and detailed structure of the polypeptide chains of protein molecules and the complementary intertwined polynucleotide chains which form the double helix in nucleic acids.Thus, proteins are built up from polypeptide chains of the type shown at the top of the next column. 

Modern concepts have been extended to the chemistry of heterocyclic compounds more slowly than to the chemistry of aromatic and aliphatic systems, but efforts are now being made to classify and explain the properties and reactions of heterocyclic compounds in terms of these newer ideas (cf. reference 11). However, many of the most important heterocyclic compounds are potentially tautomeric, and elucidation of their tautomeric composition must precede a logical treatment of their properties. Further, many natural products such as the nucleic acids and alkaloids contain potentially tautomeric groups and information of this type is needed for a detailed explanation of th reactions which they undergo,... 

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