37 



ALLEN: If it were by oxidation, you would form alcohol. 

 KAMEN: Did Sinsheimer do this? 



COHN- He destroyed the ultraviolet absorption of uracil and brought 

 it back by chemical treatment, an indication that there was no cleavage. 



CARTER: This reaction is undoubtedly different from that produced 

 by X-rays. Is the decrease produced by irradiation reversible? 



BARRON- No A good compound for study of the relationship between 

 the complexity of a molecule and its resistance to X radiation is ademne. 

 (Table III). When an aqueous solution of adenine 



NH2 



>C\ 



N C N^ 

 HC^ C^ n/ 



^n/ h 



TABLE III 



COMPARATIVE EFFECT OF X IRRADIATION ON THE 

 ABSORPTION SPECTRUM OF ADENINE COMPOUNDS. 



Concentration, 4 x lO'^ M dissolved in water, ^-ray exposure, 20, 000 r. The 

 figures given are the decTiase in optical density (log I^ ) after irradiation and 

 measured at 2600 a. 



Substance 



Adenine 

 Adenosine 

 Adenylic Acid 

 Adenosine diphosphate 

 Adenosine triphosphate 



o 



^, 2600 A 



-0.090 

 -0.045 

 -0.035 

 -0.023 



