Desoxyribose nucleic acid

Previous theoretical treatments of the transition between the helicel and random forms of the desoxyribose nucleic acid (DNA) molecule are extended to Include formally the explicit consideration of the dissociation into two separate chains and the consideration of the effects of the.ends of the chains, An approximate form for the fraction of the base pairs that are bonded is obtained in terms of two parameters, a stability constant for base pairing and a constant representing the interaction of adjacent base pairs. The matrix method of statistical mechanics proves to be adaptable to this problem. Some numerical examples are worked out for very long molecules, for which case it is found that the effect of concentration is small. 

Following the discovery of methods for the preparation of nucleic acids, Iwanoff studied the action of various molds on desoxyribose-nucleic acid, and the results led to his postulating the existence of a specific nucleoclastic enzyme, or enzymes, which he termed nuclease. ... 

In 1935, Levenc and Tipson established the furanose structure of thymidine and suggested that the other nucleosides of desoxyribose-nucleic acid are likewise furanose. On this assumption the phosphoryl groups must be situated at positions (3) and (5), and they therefore suggested " the following formula for the tetranucleotide of desoxyribose-nucleic acid. 

Swift H. (1950). The costancy of desoxyribose nucleic acid in plant nuclei. Proc. Natl. Acad. Sci. USA 36 643-654. 

Since the 1953 paper by Watson and Crick on a structure for desoxyribose nucleic acid, the structural and functional importance of base pairs linked by hydrogen bonds (H-bonds) is one of the central themes of molecular and... 

The functional determination of the use of the alternative paths has been studied extensively in a single case, the aerobic growth of E. coli on a mineral medium containing glucose, and the effect of multiplication of the bacterial virus T2, T4, or T6 within these cells in the same medium. Although the O2 consumption and R.Q. of the cells on glucose is the same in both instances, the products are quite different. Whereas a normal cell divides after producing normal cellular constituents with a ratio of ribose nucleic acid (RNA) to desoxyribose nucleic acid (DNA) of about 3 1 to 5 1, the T2 virus-infected cell almost exclusively synthesizes virus constituents, which are rich in desoxyribose nucleic acid (see Fig. 25). No... 

Thymo-nucleic acid, desoxyribose nucleic acid. Yeast-nucleic acid, ribose nucleic acid. 

The test depends on the 2-desoxyribose component of the nucleic acid and in experiments directed towards the synthesis of this sugar and its derivatives, the diphenylamine reaction has been used to obtain indications of the formation of the required product. Originally it was claimed that the test was specific for 2-desoxyribose but more recent investigations by Stacey and his coworkers48 have shown that the test is given by 2-desoxypentoses generally. Moreover, these workers have elucidated in part the mechanism of the test.48 These studies will be discussed more fully subsequently. 

Cohen66 introduced the tryptophan reaction for the detection and estimation of desoxyribonucleic acids. Since the reaction is given equally well by 2-desoxyribose, the test obviously depends on this component of the nucleic acid. It is likely that this test is given generally by 2-desoxypentoses. In the recommended procedure the suspected nucleic acid is heated at 100° for 10 minutes with tryptophan and 30 percent (final concentration) perchloric acid, and in a positive test there is a rapid development of a red color. Quantitative estimations can be carried out... 

The perchlorates of various secondary amines, such as diphenylamine and indole derivatives, are colorless.64 The similarity of colors produced in the presence of hydrochloric acid also attests to the non-auxochromic character of the perchlorate ion in the production of the colored derivative. Consequently, the only role attributable to the perchloric acid in this test is that with nucleic acids it leads to more effective hydrolysis and releases more 2-desoxyribose for reaction with tryptophan. This reaction leads to the production of a substance of the type represented by XV and XVI (R " = H), and the increase in the number of conjugated double bonds results in the product being colored. With ribose, which has a free hydroxyl group at carbon atom 2, a ketone of the type shown in XVII can be formed, and in this case the net result is no increase in the number of double bonds conjugated with the indole nucleus and no comparable increase in color. Hence the test will distinguish between ribose and 2-desoxyribose. 

Attempts have been made to estimate 2-desoxyribose by the orcinol reaction94-97 for pentoses, but in the test the desoxysugar is mainly converted into levulinic acid which gives no color with the reagent. Consequently, in tests for nucleic acids the intensity of the color given by desoxyribonucleic acid corresponds to only about one eighth of that obtained with the same quantity of ribonucleic acid.46 50-98... 

L. A. Manson and J. O. Lampen, Some chemical properties of desoxyribose nucleosides, ]. Biol. Chem., 191 (1951) 87-93 For a review of applications involving nucleosides and nucleic acids, see G. Schmidt, Periodate oxidation of ribonucleic acids and their derivatives. Methods Enzymol, 12, (1968) 230-235. 

Copley Medal for his and his two associates discovery that DNA was the substance of heredity. On this occasion. Sir Henry Dale, the President of the Royal Society said, Here surely is a change to which. .. we should accord the status of a genetic variation and the substance inducing it—the gene in solution, one is tempted to call it—appears to be a nucleic acid of the desoxyribose type. Whatever it be, it is something which should be capable of complete description in terms of structural chemistry (italics added) [31],... 

PNA pentose nucleic acid, desoxyribose nu cleic acid... 

Two methods, the one based on the alkali lability of RNA and the other on the acid lability of both RNA and DNA, appeared simultaneously in 1945 and have provided the analytical foundation for much of the recent research activity revolving about nucleic acids. The former of these methods is that of Schmidt and Thannhauser (abbreviated here as ST) (91) which depends upon the selective conversion of RNA phosphorus to organic acid-soluble phosphorus (mononucleotides) by alkali after removal of acid-soluble phosphates and of phospholipid phosphorus (16 et ante). The method of Schneider (S) (93) extracts the same lipid-free protein precipitate with hot trichloroacetic or perchloric (95) acid which solubilizes both RNA and DNA the estimation of each in the mixture utilizes specific colorimetric reactions for the (purine) ribose and desoxyribose moieties. These two methods will be discussed in connection with the combined method which follows. 

RNA is synthesized in the latter case, and since the DNA synthesis is stimulated about fourfold, there appears to be a shunt of ribose phosphate synthesis to desoxyribose phosphate synthesis in virus infection. Since nucleic acid P accounts for about 80% of the phosphorus of the cell, it is evident that this redistribution of pentose P involves a major redistribution of phosphorus metabolism. 

The pentose is either D-ribose, CjHjoOg, or D-2-desoxyribose, C5H1QO4, and accordingly two types of nucleic acid are known. 

Thy mo-nucleic acid, foimd in thymus, spleen, pancreas, liver, kidney, fish sperm, and other sources of animal chromatin. In this form of the acid the pyrimidines are cytosine and thjunine and the sugar is desoxyribose, which gives a positive Feulgen colour test (p. 349). 

Feulgen s Test for Nucleic Acid.—The material is hydrolysed with N/10 HCl at 60° C. for four minutes, and then treat with Schifi s aldehyde reagent (a 1 per cent, solution of rosaniline decolorised with SO2), a red colour develops if animal or thjmio-nucleic acid be present. The test depends on the presence of desoxyribose. 

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