Reactions Of Nucleic Acids Research Articles

Modification of cytosine moieties of nucleic acid with hydrogen sulfide (nucleosides an nucleotides. XXXIV).

The chemical introduction of 4-thiouridine (S4U) residues into nucleic acids was carried out by the reaction of nucleic acids with liquid hydrogen sulfide in aqueous pyridine, which caused the conversion of cytosine moieties to 4-thiouracil moieties.

The reaction of an organomercury compound with a nucleoside phosphorothioate: Implications for the prospect of electron microscopic nucleic acid sequencing

The proposal of determining nucleic acid sequences by base-specific labelmg with heavy elements and subsequent electron macroscopic observation has been formulated [ 11, but has not been put mto practice. It is generally considered that two types of problems must be resolved before this can be done. (1) A method must be avarlable for labeling each of the four bases wrth high specificity. (ii) Electron mrcroscopists must be able to locate single atoms or clusters of atoms with sufficient confidence. We are concerned here with the former of the two problems. The original approach consrsted m a search for base-specific reactions of nucleic acids wrth electron-dense reagents [2], but rt has proven difficult to modify one out of four bases exclusively and quantrtatrvely. An alternative approach is to introduce the label by m vrtro enzymatic replication or transcription of the nucleic acid using one heavy element-modified and three unmodified nucleosrde trrphosphates as substrates. Mercurated pynmrdme nucleotides were proposed for thus purpose [3] but proved not to be stable enough [4]. Nucleoside 5’-041 throtriphosphates) was used [5] as modrfied buildmg blocks for the m vitro syntheses. The sequence-specific label 1s obtained by reaction of a terpyndme platmum salt

Spheroids (axonal dystrophy) in the central nervous system of the dog. I. Light microscopic observations.

The spheroids in the brain and spinal cord were examined lightmicroscopically in 55 dogs (1 month to 18 years of age). Their shape varied from round to oval and was sometimes ellipsoidal or irregularly elongated, and the size ranged from 5 to 200μm in diameter. The spheroids were acidophilic and argyrophilic, histochemically positive for protein reaction but negative for nucleic acid reaction. As a new finding, PAS positive concentric round bodies were found within the spheroids in aged dogs. In the brain, the most constantly affected area was the dorsal column nuclei, especially in the gracile nucleus in the medulla oblongata. In the spinal cord, caudal segments from the lumbar to the cauda equina were noticed as the predilection sites, and the spheroids were more frequently found in the substantia intermedia hnd ventral column. The occurrence of the spheroids tended to increase with age and was marked in chronic wasting disease such as tumor cachexia and severe filariasis.

Reaction selectivity and molecular association in photochemical reactions of nucleic acids and their constituents

Abstract

Tritium labelling of nucleic acids accompanied by conversion of cytosine to uracil.

A new method of incorporation of tritium into nucleic acids with an accompanying conversion of cytosine to uracil is proposed. The method is based on the reaction of nucleic acids with bisulfite in the presence of 3H2O. Under certain conditions poly(C) is quantitatively converted to a radioactive poly(U), whereas similar bisulfite treatment of poly(U) does not result in any tritium incorporation. Specificity of the reaction is confirmed by the results of analysis of modified tRNA and rRNA. Incubation of tRNA with bisulfite and 3H2O does not lead to cleavage of the polynucleotide chain. Similar treatment of the denatured DNA results in tritium incorporation into DNA which is accompanied by a conversion of cytosine to uracil. There is virtually no reaction between native DNA and bisulfite. Only certain cytosone residues in yeast tRNAVal/2a interact with bisulfate providing that reaction is carried out under sufficiently mild conditions.

Reactions of Nucleic Acids and NucleoDroteins with Formaldehyde

This chapter discusses the three main reasons for the chemical modification of nucleic acids that are available on modifying agents. These agents are used for inactivations of various kinds, for directed functional changes of nucleic acids in vivo and for the elucidation, through resulting modification, of structural and functional characteristics peculiar to synthetic or native polynucleotides. Some of these agents are useful for one, two, or all three of these purposes. One of the few agents that serve all three of them is formaldehyde. It is widely used as an inactivator of viruses to obtain vaccines and is reported to exert a cytostatic (carcinostatic) effect. It is also one of the most promising mutagenic agents affecting multicellular organisms. Formaldehyde is used extensively in structural and functional studies of nucleic acids as an agent not so much for causing denaturation as for preventing renaturation, and as a fixator of nucleic acids and nucleoproteins in electron microscope and sedimentation investigations. Recently, some progress in the structural study of formaldehyde interaction products with nucleotides and nucleic acids has been made. The chapter emphasizes on the evidence for the formation of various structures and the molecular mechanisms of biological and other effects of formaldehyde.

Photochemical reactions of aromatic ketones with nucleic acids and their components. I. Purine and pyrimidine bases and nucleosides.

Abstract— The photochemical reactions of benzophenone and acetophenone with purine and pyrimidine derivatives in aqueous solutions have been investigated by flash photolysis and steady‐state experiments.Upon excitation of these two ketones in aqueous solutions, two transient species are observed: molecules in their triplet state and ketyl radicals. The triplet state lifetimes are 65 μsec for benzophenone and 125 μsec for acetophenone. The ketyl radicals disappear by a second order reaction, controlled by diffusion. In the presence of pyrimidine derivatives, the triplet state is quenched and the ketyl radical concentration is decreased without any change in its kinetics of disappearance. Ketone molecules in their triplet state react with purine derivatives leading to an increase in the yield of ketyl radicals due to H‐atom abstraction from the purines.Steady‐state experiments show that benzophenone and acetophenone irradiated in aqueous solution at wavelengths longer than 290 nm undergo photochemical reactions. The rate of these photochemical reactions is increased in the presence of pyrimidine derivatives and even more in the presence of purine derivatives. Following energy transfer from the triplet state of benzophenone to diketopyrimidines, cyclobutane dimers are formed. The energy transfer rate decreases in the order orotic acid > thymine > uracil. Benzophenone molecules in their triplet state can also react chemically with pyrimidine derivatives to give addition photoproducts.All these results are discussed with respect to photosensitized reactions in nucleic acids involving ketones as sensitizers.

Photosensitized reactions in nucleic acids: Photosensitized formation and splitting of pyrimidine dimers

Summary Photosensitized reactions in nucleic acids can be used either to create a selective lesion or to remove U.V.-induced damages. The formation of pyrimidine dimers in DNA can be photosensitized by aromatic ketones such as benzophenone or acetophenone. Chain breaks are also produced by reaction of radicals produced upon excitation of the ketone. Radical scavengers may prevent this latter reaction. The splitting of pyrimidine dimers can be photosensitized by indole derivatives either in fluid or frozen aqueous solutions. Splitting results from a reaction of the dimer with electrons supplied by the indole ring either directly in ground-state or excited-state complexes or via the intermediate formation of solvated electrons after photoejection by the excited indole derivative.

On the reaction of nucleic acids with isoniazid

Isoniazid the tuberculostatic drug, was shown to react with ribonucleic acids under mildly acidic conditions. When yeast tRNA was treated with 10% aqueous solution of isoniazid at pH 4.2 and 37°, an extensive derivatization of cytosine residues was observed. The characteristics of this reaction are analogous to those of the semicarbazide inodification of nucleic acids, namely, (1) the reaction takes place selectively toward cytosine residues to give corresponding 4-deainino-4-isoniazido-cytosine derivatives, and (2) the internucleotide linkage of RNA chain is not affected by this treatinent.

Thermal analysis of polyanion metachromasy: effect of temperature on metachromatic solutions of nucleic acids and acid mucopolysaccharides.

Spectra of toluidine blue with acid mucopolysaccharides and nucleic acids were recorded over the temperature range 10-70°C. Metachromatic ratios were inverse, linear functions of temperature. Intercepts and slopes of the thermal plots distinguished acid mucopolysaccharides from nucleic acids. Acid mucopolysaccharide reactions were thermally reversible. Nucleic acid reactions were not strictly reversible; such behavior was not attributable to thermal denaturation. An explanation for the unusual γ-peak of ribonucleic acid-toluidine blue metachromasy is offered in terms of terminal phosphate groups of ribonucleic acid. Solution data in which the polyanion-dye ratio was approximately 1, representing typical "metachromasy," were subjected to thermodynamic analysis. These data did not fit a common equation deriving equilibrium constants spectrophotometrically by variation of reactant concentrations. This failure supported the view of metachromasy as a phenomenon primarily involving dye-dye interaction. Another equation based only on temperature variation yielded a value of –4 kcal/mole for the chondroitin sulfate-toluidine blue complex, in good agreement with similar published values obtained both in solutions and stained materials.

Reactions of nucleic acids and their components. Part VI. The reactions of formaldehyde with cytosine, cytidine, and deoxycytidine

The reactions of formaldehyde with cytosine, cytidine, and deoxycytidine have been investigated, by spectrophotometry and the pH depression method, over the temperature range 20–50°. It was established that both the neutral and cationic forms of each compound react and that each reaction involves only one molecule of formaldehyde per molecule of the nucleic acid component. The free energies, heats of reaction, and entropy values have been evaluated.

Reactions of nucleic acids and their components. Part V. The reaction of acid imino groups of purine, thymine, and adenine with formaldehyde

Ionisation and thermodynamic constants of the acid imino groups of purine, thymine, and adenine have been evaluated, and the reaction of these groups with formaldehyde followed using the pH elevation and pH-statting methods and spectrophotometry. The free-energy changes, entropy changes, and heats of reaction have been evaluated over the temperature range of 20–50°. The reaction attained equilibrium rapidly. The results are interpretable in terms of a reversible reaction of one formaldehyde molecule with the respective acid imino group.

Reactions of nucleic acids and their components. Part VI. Thermodynamic constants of the ionisations of cytosine and cytidine

Ionisation and other thermodynamic constants of cytosine and cytidine have been evaluated at various ionic strengths and temperatures, using spectrophotometry and potentiometry. The formaldehyde reaction was used to allocate the first pk(acid) ionisation to the C6-“amino”-group.

Toxin of Pasteurella multocida

Toxic substance was isolated from the French presure cell extract of Pasteurella multocida avian type through ammonium sulfate fractionation, hydrochloric acid precipitation, Sephadex gel filtration, manganese chloride precipitation, calcium phosphate gel chromatography and zone electrophoresis.The substance was shown to be a single component by ultracentrifugation and agar diffusion test. The sedimentation constant in M/15 phosphate puffer (pH 7.0, i=0.16) for the toxin is Sw20=2.99×103.Total nitrogen of this substance was 16.3% ond showed the absorbtion of maximum in 280mμ, while negative in sugar and nucleic acid reaction, thus it was to be protein.

155. Reactions of nucleic acids and their components. Part III. The interaction of adenine and uracil with formaldehyde

The first page of this article is displayed as the abstract.

炭疽菌の特異ならびに非特異抗原性物質に関する研究特にAscoli反応に用いられる抗原性物質の分析

1. A antigenic substance was isolated from the heated cell extract of B. anthracis through trichloroacetic acid treatment, the removal of lipids by ether, aceton-, ammonium sulfate-fractionation and zone electrophoresis.2. The substance was shown to be a single component by zone electrophoresis, ultracentrifugation and agar diffusion test.3. The precipitating titer of the substance for anti-anthracis serum was positive in 2, 048×103fold dilution.4. The substance was nonspecific in the sense that it reacted with anti-B. megatherium (B. cereus) and anti-B. subtilis serum.5. The substance was positive in molisch and anthrone reaction and negative in protein and nucleic acid reaction; thus it was to be polysaccharide.

276. Reactions of nucleic acids and their components. Part I. The reaction of acid imino- and thiol groups with formaldehyde

The first page of this article is displayed as the abstract.

277. Reactions of nucleic acids and their components. Part II. Thermodynamic constants of adenine

277. Reactions of nucleic acids and their components. Part II. Thermodynamic constants of adenine

The determination of nucleic acids by their reactions with cysteine and sulfuric acid

The reaction of nucleic acids with cysteine in sulfuric acid and the use of TCA for their extraction from tissue have been reinvestigated. Modified procedures have been developed for the determination of DNA and RNA in certain animal tissues and tissue fractions. The interference of DNA in the determination of RNA was eliminated by exploiting the instability of DNA in hot TCA solutions. Complete extraction of nucleic acids was accomplished by two separate extractions with 10% TCA, 8 min. for DNA and 40 min. for RNA. Among samples ranging from 0.1 to 4% DNA phosphorus and from 0.1 to 0.6% RNA phosphorus, the average accuracy was approximately ±0.05% phosphorus in either procedure.

Nucleic Acid and Plasmacytic Reaction

In an attempt to determine whether depolymerized desoxyribonucleic acid, a product of decomposed lymphocyte nuclei, may produce plasmacellular response in lymph nodes or not, the following experiments were carried out: Different amounts of desoxyribonucleic acid (DNA), i. e. 10mg and 2.5mg DNA dissolved in 1ml of physiological saline (pH was corrected by adding N/10-NaOH approximately to 7.0), were injected subcutaneously into the foot-pad of the right hind legs in a series of adult rabbits, and cellular response in the regional lymph nodes (popliteal nodes) was observed in sections. As control, 1ml of physiological saline was injected into the foot-pad of the left hind legs.Following DNA injection, a marked infiltration of pseudoeosinophilic leucocytes occurred in both the sites of injection and the regional lymph nodes within several hours, and then disappeared gradually after 48 hours. The plasmacytes which are normally present in the medullary cords of the nodes, also increased in number to some extent, coincident with the infiltration of pseudoeosinophiles. But their increase was not significant as compared with the controls, because injection of physiological saline alone produced a similar increase of plasmacytes (Tables 1 and 2). The cellular response in the sites of injection was almost the same as observed in the regional lymph nodes.It is concluded from these findings that depolymerized DNA, a product of decomposed lymphocyte nuclei, cannot be regarded as a primary factor to produce plasmacytic reaction in lymph nodes.