Ribonucleic Acid, Hydrolysate

It is now known that mild, alkaline hydrolysis of ribonucleic acids yields mixtures of the 2 - and 3 -phosphates of ribonucleosides, although it had earlier been believed that only the 3 -phosphate derivatives are produced. For example, it was reported that guanylic acid (6), obtained from ribonucleic acid hydrolysates, is deaminated with nitrous acid to xanthylic acid (7), which was hydrolyzed at pH 1.9 to a ribose phosphate... 

The nucleases are enzymes that hydrolyse nucleic acids, either deoxyribonucleases (DNases) that have DNA as the substrate or ribonucleases (RNases) that have ribonucleic acids as the substrate. The DNases hydrolyse the phosphodiester linkages between the deoxyribose molecules of DNA, and similarly, the RNases attack the equivalent bonds in RNA. There are many nucleases found in mammalian tissues, and as in the case of the peptidases, they can be divided into the categories endo and exo based on whether they attack bonds in the interior of the nucleic acid molecule or remove nucleosides from the end termini of the chains. They... 

Oxidation of (8) yielded a ribonic acid phosphate (9), whose properties differed from those of the ribonic acid 5-phosphate obtained by similar hydrolysis and oxidation of inosine 5 -phosphate. Moreover, reduction of (8) allegedly gave a ribitol phosphate (10) which was optically inactive. From these studies, it followed that the phosphoric moiety in (10) is esterified by the 3-hydroxyl group of the ribitol moiety. Similarly, a yeast adenylic acid, obtained from an alkaline hydrolysate of yeast ribonucleic acid, was deaminated to an inosinic acid that was different... 

The reaction between [AUCI4] and ribonucleic acid can be followed spectro-photometrically. The reaction is first order with respect to gold and second order with respect to the nucleotide unit of RNA. pH and ionic strength dependences of the reaction rate indicate that various hydrolysed gold(iii) species are probably involved in the reaction. ... 

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. 

Nucleic acids are degraded by concentrated salt solutions and heat is also harmful. Even dilute acids attack nucleic acids and dilute alkali hydrolyses ribonucleic acids rapidly. 

Procedure 10 mg ribonucleic acid are maintained for 20 h at 37° with 1 ml 0.2 N sodium hydroxide. After cooling, the hydrolysate is acidified with 0.5N hydrochloric acid (pH 4—6) and the acid solution used for analysis of the mononucleotides. 

Ribonucleic acids are not completely hydrolysed under these conditions. 

Mononucleotides in alkaline hydrolysates of ribonucleic acids are best separated on PEI-cellulose and quantitatively determined after elution. In a recommended procedure, the individual fractions are eluted with M lithium chloride on to a narrow paper strip, the strip is dried, the nucleotides are eluted from it with water and the concentrations of the aqueous solutions determined by spectrophoto-metric measurements in the UV [57] considerably more accurate analyses are possible with this procedure than by direct extraction from the adsorbent [57] (see also Fig. 54, p. 104). 

Complete separation of the mononucleotides in alkali hydrolysates of ribonucleic acids is possible in 75 min through electrophoresis (450 V) on a cellulose layer, sprayed with sodium formate buffer of pH 3.4 [17] (see also [97]) 10—20 h are needed for paper electrophoresis of these compounds [15]. Mixtures of mononucleotides have also been separated by two-dimensional thin-layer electrophoresis-chromatography on cellulose [3]. 

Ribonucleases (RNases) are enzymes that specifically hydrolyse the phosphodiester bonds in ribonucleic acid (RNA). They are distinct from general nucleases which digest both RNA and deoxyribonucleic acid (DNA), from deoxyribonucleases (DNases) which digest exclusively DNA, and from phosphodiesterases... 

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