monolayer and irradiated, then its antigenic property is lost or its 

 ability to combine with antibodies is lost, but it is lost after consid- 

 erably more radiation than will remove its solubility. 



Now, to start the discussion, I should like to suggest that we have an 

 explanation for these events. This is largely aimed at Dr. Platzman. If we can 

 get him started we have succeeded. 



We feel that two things occur. I rather like the method of approach that 

 is used by Augenstine in the remarkable little book on "Information Theory In 

 Biology", that Quastler edited (University of Illinois Press, 1954). Augenstine 

 analyzed protein denaturization in the following stages: 



1. The breaking of a bond such as an S-S bond, which is a definite 

 strong bond. This is associated with no entropy change and in- 

 volves an energy change of about 20,000 calories per mole. 



2. The breaking of a number of hydrogen bonds which opens the struc- 

 ture. They have entropy associated with them, and each has a much 

 smaller amount of actual energy, in the neighborhood of 6000 calo- 

 ries per mole. 



3. Another bond is joined, and, in Augenstine's approach, this is a 

 newS-Sbond, not the right one for the original configuration. 



We should like to take almost exactly the same viewpoint for radiation 

 action. Being a physicist, I know no chemistry and, therefore, I shall justdraw 

 the whole structure. 



A physicist's idea of a protein backbone, with cross-linkages here and 

 there is shown in Figure 1. 



I 1 



I SUBSTRATE | 



Cross linkage 



Figure 1. Schematic representation of 

 events associated with the passage of a 

 fast-charged particle through a protein 

 molecule. 



What is said about protein obvi- 

 ously can apply to nucleic acid also. 

 Let us imagine that the particle tra- 

 verses the molecule as shown in the dia- 

 gram. This is the path of the fast- 

 charged particle that does the ionizing. 

 We will say that all it does is produce a 

 primary ionization at A. As a result of 

 the primary ionization, first of all, a 

 plus is formed at A and then an electron 

 is also released. We will say that the 

 path of the electron is as indicated and 

 that it ionizes again at B and then moves 

 away. There are now two electrons 

 produced, one of which comes to rest 

 while the other ionizes at C before com- 

 ing to rest. There are now three pluses 

 and three minuses where electrons have 

 been captured. Now all this must hap- 

 pen in the order of 10" ^3 seconds, per- 

 haps even less because very little time 

 is required. 



What follows this and how it is 

 related to the loss of biological function 



