684 



ADVENTURES IN RADIOISOTOPE RESEARCH 



Ratio of the specific activities of 



ribosenucleic acid P 

 desoxyribosenucleic acid P 



A 

 B 



1.96 

 2.06 



Table 3. — "Pekcentage Formation" of Nucleic Acids in the Jensen-Sabcoma 



OF THE Rat(1) 



(Time = 2 hours) 



Ratio of the "P content of ribosenucleic acid and desoxyribosenucleic acid in the Jensen-sarcoma = 2.4 



O We came to tlie "Percentage Renewal" figures, contained in the above Table by comparing the end 

 values of the specific activities of the nucleic acid P and inorganic, P. Correctly, we have to consider the mean 

 value of the specific activity of the inorganic P during the experiment. The correction to be applied to arrive 

 at correct figures is discussed on p. 685. 



<') In this experiment the specific activity of the pyrophosphate P was determined as well. Tlie ratios 

 of the specific activities of pyrophosphate P : plasma inorganic P : sarcoma inorganic P was 1 : 1.10 : 0.97. 



Similar values for the rate of formation of ribosenucleic acid and of 

 desoxyribosenucleic acid were obtained in a number of other experiments, 

 the result of which are summarized in Table 3. The average value, 

 obtained for the percentage new -formation of desoxyribosenucleic acid, 

 1.9, compares fairly well with the average value, obtained in our 

 previous investigations (2.05, 2.17), which involved a very large 

 number of determinations. 



In all our previous work^^) the desoxyribosenucleic acid P was purified 

 from contaminating phosphorus compounds by repeated alternative 

 boiling with cone. NaOH and reprecipitation of the dissolved desoxy- 

 ribosenucleic acid P with methanol, containing HCl. This method has 

 the disadvantage that a poor yield is obtained. The method of Schmidt 



^i^ H. EuLEB and G. Hevesy, Kgl. Danske 

 17, No. 8 (1942). 



Videnskab. Selskab. Biol. Medd. 



