Nucleic acids : their chemical properties and physiological conduct / by Walter Jones.

  • Jones, Walter, 1865-1935
Date:
1920
Catalogue details

Licence: In copyright

Credit: Nucleic acids : their chemical properties and physiological conduct / by Walter Jones. Source: Wellcome Collection.

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    D But the relation of nuclein to protein remains to be considered. The presence of a salt, protamine nucleate, in the metamorphosed nucleus suggests the presence of protein nucleate in the original nuc- leus ; or that nuclein is simply a salt of protein and nucleic acid.1 This p assumption cannot be definitely proven, but is supported by a large amount of evidence, and any other conclusion leads to complication without purpose. 1. Nucleic acids are polybasic acids and proteins are polyacid bases, so that a large number of salts of the two substances are to be expected. One of these salts will have a greater resistance to pepsin than the others, and will be formed as an end product of the action of pepsin upon any other salt having a greater proportion of protein in its composition. 2. The nucleins are not entirely unaltered by pepsin, they are only somewhat resistant to its action (Umber [1901]). 3. Artificial nucleins resistant to the action of pepsin are formed as immediate precipitates when faintly acid solutions of protein and nucleic acid are brought together (Milroy [1896]). 4. Brief contact of nucleins with dilute caustic soda renders the protein part precipitable by acetic acid (Altmann [1889]). 5. From solutions of nuclein, picric acid precipitates the protein, leaving the nucleic acid in solution (Levene [1901]). 6. The presence of protein is apparently without influence upon the decomposition of nucleic acid by the action of ferments. 7. A solution containing both nucleic acid and protein has an optical rotation equal to the algebraic sum of the rotations of the two constituents (Osborne [1903]). In the year 1889 Altmann [1889] described a method of preparing protein-free nucleic acids from animal tissues and from yeast, when the interest which had previously been taken in nuclein began to decrease. Subsequently, Kossel and Neumann [1894, 1] devised a method of preparing nucleic acid from the thymus gland. Under the most favourable conditions their procedure gives only passable results and requires the greatest care in its execution, but it furnished Kossel and Neumann the material for their wonderful researches on nucleic acid and made Kossel considerably less interested in nuclein. Finally Neumann [1899] showed how nucleic acid can easily be prepared from all of its common sources except yeast (Kowalevsky [1910]) and in such quantity as to place the substance within easy reach of 1 Like the heads offish spermatozoa, the tubercle bacillus contains protamine nucleate (Rupple [1898]).