RADIATIONS AND COENZYMES 



231 



on irradiation of ribose nucleic acid and thymonucleic acid with 2 X 10^ 

 r. However, even in these experiments the part played by oxidation 

 can be determined by the greatly diminished formation of NH3 when 



1.0 



1. Control 



2. 100,000 r 



0.20 



0.24 ^ 

 X 10^ A 



0.28 



Fig. 11. Effect of x-ray irradiation on the 

 absorption spectrum of adenosinetriphos- 

 phoric acid (muscle). Abscissa: Wave- 

 length in angstrom units; ordinate: optical 

 density E. 



Fig. 12. Effect of x-ray irradiation on the 

 absorption spectrum of diphosphopyridine 

 nucleotide. Abscissa: Wavelength in ang- 

 strom units; ordinate: optical density E. 



irradiation was performed in vacuum. The absorption spectrum of 

 sodium desoxyribonucleate was less altered on irradiation with x-rays 

 (Fig. 13). It is quite possible that the primary alteration is in the 

 viscosity when the nucleic acid combines with the basic protein (15). 

 It may be predicted from these studies that the sensitivity to ionizing 



