41 



FANO: How much water is in protein? 



POLLARD: As far as I am concerned, we need to talk about whether there 

 is a place where the electron is admittedly more likely to be trapped in the im- 

 mediate locale. Is there a place in the polypeptide chain where on its way back 

 to the positive ion it can do positive damage? Is so, where is the likely place 

 and let's think about that as a very important radiobiological process? 



KAMEN: What is the ionization and what is the source of the electron? 



POLLARD: Well, it has been kicked out of the atom. 



KAMEN: What atom? 



POLLARD: The carbon, hydrogen, nitrogen, phosphorus, or sulfur. 



KAMEN: The best thing I can do is to take an amino acid like alanine and 

 ask what happens. 



KASHA: The electron would come off the oxygen probably, and form a free 

 radical which would then dismute and give off CO^ and then the electron mean- 

 while -- 



BURTON: Why do you form a free radical when you take an electron off 

 something? Why does it immediately decompose? 



KASHA: A charged radical is formed. 



BURTON: Why do you have to produce it? What you produce initially is an 

 ion. 



ALLEN: It has an odd number of electrons. 



BURTON: The electron moves some place and you leave an ion behind. It 

 does not necessarily follow that the ion is chemically unstable. The ion might be 

 stable. 



ONSAGER: That is uncertain. 



KASHA: This electron is not a bonding electron so that it would probably be 

 stable. Wouldn't the two electrons be the non-bonding electrons of the oxygen? 



BURTON: There is no requirement that it be any particular electron. You 

 can get any electron out. 



KAMEN: I think when you have a rearrangement of the electrons you are 

 bound to break something. 



LINSCHITZ: It is a known practice to make radical ions in various rigid 

 solvents by photo-ionization. They may be quite stable if you can avoid back 

 reaction with the ejected electron (Lewis and Lipkin (15) ). We are going to 

 talk at some length about that process in the fourth session. 



KAMEN: The only things that are pertinent here are the data by those who 

 have done the work. I imagine Dale has irradiated solid alanine and solid amino 

 acid, has he not? 



