286 



PETER REICHARD 



TABLE VI 



Incorporation of Radioactive Precursors into Purines from 



Polynucleotides by the Rat'* 



C* precursor 



CO2 



Formate 



Glycine-1-Ci^.. 

 Glycine-1,2-C'^ 



C'* specific activity, counts/min./mM. carbon 



Adenine 



130 



4,550 



270 



65 



Guanine 



170 



5,760 



300 



75 



Guanine carbon no. 



4 + 5 



35 







530 



115 



1,220 

 135 



770 



10 



16.400 



10 











12.500 



10 







Glycine-2-Ci* also contributed a considerable part of its label to position 2 

 (position 8 was not investigated), which is in agreement with the earlier 

 findings of Karlsson and Barker.^" 



The sources of the nucleic acids and the methods of preparation which 

 were used in the above-mentioned studies on the biogenesis of polynucleo- 

 tide purines make it appear probable that the purines studied were either 

 derived mostly from pentose nucleic acid (PNA) or were obtained from a 

 mixture of PNA and deoxypentose nucleic acid (DNA). No investigations 

 have been reported in which purines from DNA alone have been isolated 

 and degraded after administration of labeled compounds. There is, however, 

 no indication, that the biosynthetic pathway for these purines should 

 differ from that of PNA purines. It has been shown by Bergstrand el al.*^ 

 and by Reichard'*^ that glycine-N^^ is utiUzed for the synthesis of DNA 

 purines in different organs of the rat. LePage and Heidelberger^^ found 

 that glycine-2-C''' is incorporated into the DNA purines from rat liver and 

 that this incorporation is of the same order of magnitude as that found in 

 the PNA purines. Elwyn and Sprinson''* demonstrated that in the rat 

 both glycine-2-C'** and serine-3-C^* were incorporated into DNA purines 

 to about the same extent as into PNA purines. Totter et al.^^ found that for- 

 mate-C^^ was utilized by the rat for synthesis of both DNA purines and 

 PNA purines from the viscera. These results have been confirmed by Gold- 

 thwait and Bendich.'*^ 



« A. Bergstrand, N. A. Eliasson, E. Hammarsten, B. Norberg, P. Reichard, and 



H. von Ubisch, Cold Spring Harbor Symposia Quant. Biol. 13, 22 (1948). 

 «P. Reichard, J. Biol. Chem. 179, 773 (1949). 



" G. A. LePage and C. Heidelberger, /. Biol. Chem. 188, 593 (1951). 

 « D. Elwyn and D. B. Sprinson, J. Am. Chem. Sac. 72, 3317 (1950). 

 ^« J. R. Totter, E. Volkin, and C. E. Carter, J. Am. Chem. Soc. 73, 1521 (1951). 

 " D. A. Goldthwait and A. Bendich, J. Biol. Chem. 196, 841 (1952). 



