Ribonucleic acid precipitation

In a number of methods, isolation of the nucleoprotein complex (stage 2) is avoided. In the isolation of ribonucleic acid from beef pancreas,1241 nuclear material and cell debris are removed from a normal-saline extract of the minced tissue, which is then brought to half-saturation with sodium chloride (to dissociate the protein from the nucleic acid). After removal of the protein, the nucleic acid is precipitated with alcohol. However, the suggestion has been made126 that it is more satisfactory to isolate the nucleoprotein first, and this has been carried out, for instance, in the extraction of the ribonucleic acid from fowl sarcoma GRCH 15.126 Nucleoprotein complexes have also been isolated from baker s yeast127 and have been separated into various fractions, the nucleic acids from which differ slightly in composition. In addition, nucleoproteins have been isolated by complex formation with cetyltrimethylammonium bromide.128... 

Insulin in vitro increases the recovery of glucose carbon in the trichloroacetic acid-precipitable protein of epididymal adipose tissue from fasted rats (Herrera and Renold, 1960 Carruthers and Winegrad, 1961), and also increases the incorporation of glucose carbon into the ribonucleic acid fraction of adipose tissue from fasted rats (Carruthers and Winegrad, 1962). That these latter effects were observed in the presence of unlabeled glycine suggests that the bulk of the incorporation was into the pento.se moiety. When adipo.se ti.ssue from fasted rats is incubated with pyruvate- -C pyruvate carbon is isolated in the ribonucleic acid fraction however, the addition of insulin does not affect this incorporation (Carruthers and Winegrad, 1962). 

The nucleic acids were discovered by Miescher in 1868-1869, when he isolated from pus cell nuclei a material which contained phosphorus, was soluble in alkali, but precipitated under acidic conditions. This material was subsequently prepared from other sources and when freed from protein it was called nucleic acid, a term introduced by Altman in 1889. The classical preparations of nucleic acid from yeast yielded a product which we now recognize as ribonucleic acid (RNA). The nucleic acid prepared from thymus glands, thymonucleic acid, was also extensively studied this material [which, in present terms, was deoxyribonucleic acid (DNA)) was different from yeast nucleic acid. From hydrolysates of these preparations the heterocyclic bases were isolated and characterized. At one time, yeast and thymus nucleic acids were thought to be representative of plant and animal nucleic acids, respectively (3). By 1909, it was apparent that yeast nucleic acid contained adenine, guanine, cytosine, uracil, phosphoric acid, and a sugar which Levene showed at that time to be D-ribose. Thymonucleic acid yielded adenine, guanine, cytosine, thymine, phosphoric acid, and a sugar which was not identified correctly until 1929, when it was characterized as 2-deoxy-D-ribose. 

The procedure of Snoke is exceedingly simple. An acetone powder of the liver is extracted with phosphate buffer, and inert protein precipitated by a mixture of ribonucleic acid (RNA) and 20% by volume of ethanol. Upon adjusting the supernatant fluid to pH 6.25 at —5° the enzyme comes down in the precipitate formed. This is dissolved in water and 0.6 volume of... 

Philipps, G. R., West, J. Purification of protamine sulfate for the quantitative precipitation of ribonucleic acids. Biochim. biophys. Acta (Amst.) 91, 416—420 (1964). 

Although the anti-poly G poly C sera react with poly dG poly dC, no precipitation with Micrococcus lysodeikticus DNA (72% GC) is observed, whether native or heat-denatured DNA is used. Negative results are also obtained with native or denatured DNA from E, coli, Clostridium j>erfringens, phage 2 C, chicken myeloblastic leukemic cells or calf thymus. In contrast, antibodies to poly G poly C react with RNA and appear to be capable of distinguishing ribonucleic acids according to their origin. 

Both nuoleoproteins were precipitated with calcium chloride and dexosyribonucleo-protein was separated by treatment with sodium chloride. Ribonucleic acid w purified by precipitation of the barium salt and subsequent precipitation of the free acid in glacial acetic acid. 

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