46 



thousands, like the photochemical chain reactions. 



CARTER: Isn't it conceivable that in some systems, an enzyme would 

 split a substrate more rapidly because of the radiation energy that has been ab- 

 sorbed into the system? 



POLLARD: Very little energy is put in there measured in terms of 

 the metabolism of the cell. 



CARTER: I think, in one of the cases you mentioned this morning, 

 the enzyme protein was acting upon the substrate. Can any of the energy that is 

 absorbed into the protein be transmitted into the enzyme substrate complex? 



POLLARD: It certainly can be, but that would affect only the one sub- 

 strate molecule that happens to be on the protein at the same time, and the en- 

 zyme is good for several thousand. 



CARTER: And the molecular transformations are taking place much 

 slower. 



POLLARD: I feel that we are ignoring the innate character of radiation 

 action which is that for the amount of energy it puts forth, its effect is enormous 

 -- larger than any other character of energy. That is the basic quality that ra- 

 diation has. So I don't think we ought to look upon it as though it were just a 

 form of heat or something of that sort. 



CARTER: But it propagates over long periods of time. 



POLLARD: It is an autocatalytic action of some kind. 



CURTIS: In terms of enzymes, enough radiation to kill a cell will in- 

 activate only one in every 10° molecules of the enzyme or something of that or- 

 der of magnitude. On this basis, you don't have very much of an increase in the 

 reaction. 



CARTER: Unless the substrate were on there at that time, and then 

 it is an event of very short duration. Is that the point? 



POLLARD: That is my point. 



I think that Dr. Barron's point about enhancements is a new concept in 

 this type of work, and if we agree that enhancement can occur as well as inhibi- 

 tion, we might make a lot of headway. Incidentally, the enhancement must be a 

 particular kind of enhancement and obviously, systems other than his must show 

 enhancement. So if you can find one or two that do and concentrate on them, that 

 might be very revealing for radiation action. 



ALLEN: Dr. Barron raised a point early in his talk to the effect that 

 you do not get reduction very readily in solutions in pure water. It has always 

 seemed to me that this is to be expected if the water decomposes, at least rough- 

 ly, into equal numbers of oxidizing radicals and H atoms. They ought more or 

 less to neutralize each other, so that you should get little reduction or oxidation. 



BARRON: However, you do get oxidation. 



ALLEN: In some systems, even in the absence of oxygen, you do get 



