THE STRUCTURE OF YEAST NUCLEIC ACID. 
II. URIDINEPHOSPHORIC ACID. 
By P. A. LEVENE. 
(From the Laboratories of The Rockefeller Institute for Medical Research.) 
PLATE 1. 
(Received for publication, December 1, 1917.) 
In a series of articles published in the course of the last few 
years, Walter Jones! and his coworkers advanced a theory on the 
mode of linkage of the four nucleotides taking part in the molecu- 
lar structure of yeast nucleic acid. According to these authors, 
the nucleus of yeast nucleic acid is a tetra-ribose of the following 
structure [(C;H190;)4—3 H2O]. Jones and his coworkers have 
based their conclusions on the analysis of three substances which 
they had regarded-as dinucleotides. 
In a previous publication? it was pointed out that the theory of 
Jones and his coworkers was not the only possible conclusion 
from the facts presented by them. It was further pointed out 
that not sufficient rigor had been exercised in proving the dinucleo- 
tide structure of the substances described by them. In the same 
publication the present author reported in a preliminary way the 
results of his own attempts to fractionate the pyrimidine nucleo- 
tides described by Levene and Jacobs.? For this purpose the 
crude nucleotides were transformed into the brucine salts and 
these were repeatedly recrystallized from dry methyl alcohol. 
In this manner a substance of constant composition was ob- 
tained. On conversion of the brucine salt into a barium salt, the 
composition of the substance was not altered. Both the brucine 
and the barium salt had the elementary composition of a di- 
1 Jones, W., and Richards, A. E., J. Biol. Chem., 1914, xvii, 71. Jones, 
W., and Germann, H. C., tbid., 1916, xxv, 93. Jones, W., and Read, B. E., 
abid., 1917, xxix, 123; xxyi, 39. 
2 Levene, P. A., J. Biol. Chem., 1917, xxxi, 591. 
3 Levene, P. A., and Jacobs, W. A., Ber. chem. Ges., 1911, xliv, 1027; J. 
Biol. Chem., 1912, xii, 411. 
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