128 



PATT: In other words, the solotions are irradiated in nitrogen and 

 then equilibrated with oxygen. 



CARTER: The interpretation has usually been (and I think there is 

 general agreement here) that the presence of oxygen during irradiation gives 

 rise to an increased amount of oxidizing radicals, but there is, in addition to 

 that, another factor which is apparent from Butler's data. If one takes a nu- 

 cleic acid and puts it in an aqueous solution which has been irradiated with 10"* 

 r, there is a slow, slight drop in viscosity of the high molecular weight nucleic 

 acid. If one takes a nucleic acid that has been irradiated in nitrogen and then 

 adds to it water that was irradiated in oxygen, one finds a more extensive, more 

 rapid drop in viscosity. 



Finally, this can be compared with the considerably more extensive 

 drop in viscosity of solutions of nucleic acid irradiated in oxygen. 



The formulation that arises from these data is as follows: 



Not only the oxidizing radicals formed in the aqueous solution by the 

 absorption of radiation participate in this phenomena, but irradiation gives rise 

 to oxidized groups upon the nucleic acid which can participate synergistically or 

 additively with the radicals that are formed in solution. So that there are two 

 concepts to be considered in the interpretation of these data: 



1. The radicals produced in water by the irradiation. 



2. The radicals that are formed on the high molecular weight nucleic 

 acid. 



ALLEN: Is this effect produced if you put the thing into a solution of 

 peroxide? 



CARTER: This effect is produced. This slow, small decrease in 

 viscosity. 



ALLEN: I wonder if peroxide out of a bottle will produce the same 

 effect, 



CARTER: Yes, but not nearly as efficiently. 



BARRON: I was going to ask whether the authors have measured the 

 amount of peroxide formed in water. 



CARTER: Yes, they have. 



BARRON: And this effect is not equal to the amount of hydrogen 

 peroxide from the bottle? 



CARTER: No, it is not. 



BARRON: That has been our experience also. The peroxide obtained 

 from manufacturers is different from the peroxide obtained after irradiation. 



CARTER: This is understandable, isn't it Dr. Allen? 



ALLEN: It is not understandable if the peroxide is obtained from a 

 good manufacturer. 



