106 



get out even easier. 



KAMEN: There is the other alternative that the electron is not recaptured 

 by the parent ion. 



FANO: There is the formation of a radical at some distance which amounts 

 to the same thing in the end. 



BURTON: It does not amount to the same thing in the end; certainly not for 

 the radiobiologists and I will mention that later. There is a distinct difference. 



KAMEN: The interesting thing, at least to me, is the reaction which is al- 

 ways written for electron capture in water going to OH" and H atoms. It appears 

 this is incorrect, even though A H is in its favor, because of the necessity for 

 the dipoles to orient first. This is something I never heard of before and I guess 

 nobody else in my particular bailiwick has ever heard of it. I think it is impor- 

 tant to keep in mind that as far as those of us who have to teach radiobiology are 

 concerned, we have to try to teach the truth sometimes. 



ONSAGER: A dielectric constant of 5 may be just enough to stabilize the 

 hydroxide ion. The question appears to call for more experimental and theoreti- 

 cal work. 



PLATZMAN: According to the model, a minimum of 2 electron volts is 

 needed suddenly -- perhaps as much as 4. If my calculation is right, the atomic 

 polarization won't help. 



ONSAGER: Do you mean a dielectric constant of 5 isn't enough? That is 80 

 per cent of the self- energy. 



PLATZMAN: This is a possibility, of course, but, thus far, the calculations 

 indicate otherwise. 



KAMEN: I would like to turn for a moment to consideration of protein in 

 connection with these remarks on dielectric effects. Protein is actually quite a 

 polar substance; it has a lot of free rotation and there is plenty of opportunity 

 for all kinds of motion in a protein as a result of electrostatic forces. There is 

 motion in the sense of continuous oscillation. Moreover, it is constantly being 

 broken down, and reconstituted and this is one of the things about protein that is 

 remarkable. 



POLLARD: This is not true for the backbone. It is only true for the side 

 chain amino acids. One must remember that. Schoenheimer's work is nice, 

 but it concerns only the turnover of the amino acids (4). 



KAMEN: This contention that the backbone is not involved in turnover is 

 certainly debatable. However, I don't want to get into a discussion of the turn- 

 over in protein because it isn't understood by anybody. Obviously, many radia- 

 tion situations have to wait for an explanation of non-radiation situations. Thus, 

 it should be remembered that protein inactivation can be achieved by changing 

 pH or ion environment, as well as by irradiation. To continue, one mechanism 

 for the denaturation of protein has been proposed by Franck and Platzman (5) based 

 on the splitting of hydrogen bonds, resulting from the electric field that is set up 

 by ionization, which persists long enough and is of sufficient intensity to rupture 

 something of the order of 30 hydrogen bonds for each ionization. This is an 

 enormous dissipation of heat locally. Its origin is different from that of the 

 electrostatic effects produced by thermal ions, which are slow and involve 



