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PLANT NUCLEIC ACIDS. 185
the formula C40HMN14O16.2P2O8. According to Steudel for every 4
atoms of phosphorus we have 15 atoms nitrogen and from this he has
calculated fche formula ( UaHeiN 15P4O34+9H2O for the acid containing
water.
The probable constitution of the thymo-nucleic acids has been previ-
ously indicated and as positively known cleavage products we have at least
phosphoric acid, a hexose carbohydrate, guanine, adenine, thymine and
cytosine.
The thymo-nucleic acids have the reactions as given for the complex
nucleic acids. They are amorphous, dextro-rotatory, and soluble in cold
water with difficulty. They form soluble salts with alkalies and the acid
is precipitated from these solutions by mineral acid but not by acetic
acid. Tannic acid alone does not cause a precipitate but does in the
presence of sodium acetate. Proteins precipitate their solutions contain-
ing acetic acid. The two special thymo-nucleic acids differ from each
other by the different behavior of their salts (see above).
The preparation of the nucleic acids is based in the first place always
upon the cleavage of the nucleoprotein into protein and nucleic acid by
the action of alkali and then separating the nucleic acids from the
protein. The operations necessary for purifying the nucleic acids from
proteins are very complicated and we must refer to the works of
Schmiedeberg, Neumann, Levene, and others. 1
Plant Nucleic Acids. The two best known acids of this group are
the yeast nucleic acid and the triticonucleic acid isolated from the
wheat embryo. The identity of these two acids, as suggested by Osborne
and Harris has become more and more probable. According to Kowa-
lewskt 2
the yeast nucleic acid contain only adenine, guanine and cytosine,
the uracil is only formed secondarily from the cytosine. The yeast nucleic
acid may perhaps be a triphosphoric acid with three molecules of pentose
each with a molecule of adenine, guanine and cytosine.
This view stands in opposition to the observations of Levene and
Jacobs 3
that the yeast nucleic acid contains one molecule of pentose
combined with adenine and guanine, and besides this it contains two
pyrimidinehexose complexes, cytidine and uridine.
The triticonucleic acid yields also, as Osborne and Heyl, Wheeler
and Johnson and recently Levene and La Forge 4
have shown, the same
hydrolytic products as the yeast nucleic acid and both contain rf-ribose.
Schmiedeberg, Arch. f. exp. Path. u. Pharm., 43 and 57; Herlant, ibid., 44; Neu-
mann, Arch. f. (Anat. u.) Physiol. 1899 Supplb.; Levene, Zeitschr. f. physiol. Chem.,
32 and 45; Kostytschew, 1. c.
2
Osborne and Harris, Zeitschr. f. physiol. Chem., 36; Kowalewsky, ibid., 69.
3
Ber. d. d. chem. Gesellsch., 44.
4
Osborne and Heyl, Amer. Journ. of Physiol., 21; Wheeler and Johnson, Amer.
Chem. Journ., 29; Levene and La Forge, Ber. d. d. Chem., Gesellsch., 43.
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