Full resolution (JPEG) - On this page / på denna sida - II. The Protein Substances - II. Compound Proteins - B. Nucleoproteins - Cleavage Products of the Nucleoproteins - 1. The Nucleic Acids - 2. Purine Bases
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
186 THE PROTEIN SUBSTANCES.
The somewhat different results found on the elementary analysis of these
two acids do not seem to be of very great importance and we have strong
evidence for the identity of these acids. Osborne and his collaborators
found the formula C41H61N16P4O31 for triticonucleic acid.
The plant nucleic acids have the general reactions of the complex
nucleic acids but can be precipitated by an excess of acetic acid. They
are dextro-rotatory.
In regard to their preparation we refer to the works of Kossel, Osborne
and Harris and to Levene and co-workers. 1
Plasminic acid is an acid which was prepared by Ascoli and Kossel 2
by
the action of alkali upon yeast. It contains iron, and is soluble in very dilute
hydrochloric acid (1 p. m.). It is still a question whether it is a mixture or a
chemical individual.
2. Purine Bases.
The cleavage products obtained from the nucleic acids, the nuclein
bases, which are also called alloxuric bases by Kossel and Kruger, are
members of the larger group of purines, to which also belongs the uric
acid which is a substance occurring in the animal body. The constitu-
tion of these bodies has been explained by E. Fischer,3 and he has
prepared many of the bodies synthetically. They can all be derived from
the synthetically prepared purine, C5H4N4, which has the formula given
below and which may be considered as a combination of a pyrimidine
ring with an imidazole ring.
N=CH N=CH
II II HC-NH>
HC C—NR HC CH |
>CH
II II
>CH || ||
HC N^
N—C N^ N—CH
Purine Pyrimidine Imidazole
The different purine bodies are derived therefrom by the substitution of the
various hydrogen atoms by hydroxyl, amide, or alkyl groups. In order to signify
the different positions of substitution Fischer has proposed to number the nine
members of the purine nucleus in the following way:
1N=C6
I I
2C 5C—N7
>
.C8.
3N—C—N9
4
1
See footnote 2, p. 179, and footnote 3 and 4, p. 185.
2
Ascoli, Zeitschr. f. physiol. Chem., 28.
3 Sff ]’.. Kisr-her, Untersuchungen in der Purinfjrwppe (1882-1906) Berlin, 1907.
<< prev. page << föreg. sida << >> nästa sida >> next page >>
