MOLECULAR COMPLEMENTARINESS IN ANTIGEN-ANTIBODY SYSTEMS 17 



Pressman, D. and M. Siegel. 1953b. The steric configuration of 3-benzoylpropionate 



ion in aqueous solution as determined by immunochemical means. J. Am. Chem. 



Soc. 75: 1376^1379. 

 Pressman, D., M. Siegel and L. A. R. Hall. 1954. The closeness of fit of antibenzoate 



antibodies about haptens and the orientation of the haptens in combination 



J. Am. Chem. Soc. 76: 6336-6341. 

 Siegel, M. and D. Pressman. 1953. The reactions of antiserum homologous to the 



p-azohippurate ion. J. Am. Chem. Soc. 75: 3436-3439. 



Chairman Pauling: (Repeating question from audience) I would like to 

 ask Dr. Pressman if he has examined the specificity and how far the specificity 

 which he has determined with respect to antigen antibodies in hapten combina- 

 tion occurs over other systems? For example, he pointed out combination 

 constants where he has substituted benzoic acids with respect to his haptens. 

 What happens with sulfonate in the system? Would you expect highly sub- 

 stituted sulfonic nitrogen to inter-react with one of your benzoic acid haptens, 

 or not, or with inhibitors? 



Dr. Pressman: The question is whether or not the acid is an inhibitor in 

 the sulfonylamide system. We measured the extent of combination of anti- 

 bodies prepared against para-azobenzoate with sulfonylamide and found no 

 combination. Now, our antibody was directed against the azobenzene carbox- 

 ylate ion, and the question comes up as to how the receptor site for sulfonyla- 

 mide or the receptor site for a paraminobenzoate ion in the appropriate enzyme 

 systems is oriented toward the ion? 



It may well be that the para-amino group is the more important group with 

 the charge group oriented in opposite direction from that in our study. This 

 is a problem which I have wanted to investigate for some time to see if I can 

 discover how the receptor for the para-aminobenzoic acid and the sulfonyla- 

 mide compare with each other. This would require orienting the para-amino 

 benzoate molecule in the antigen in various ways for the preparation of anti- 

 body or in orienting with sulfonylamide molecules in various ways, in its 

 attachment to a prospective antigen, to form a proposed antibody which could 

 subsequently be studied. I think that this is a very important problem which 

 might well yield results with further investigation. 



Chairman Pauling: I might mention another example. In the serological 

 experiments the methyl group and the chlorine atom are not exactly identical 

 but quite similar in their functions. Their shape is nearly the same; they differ 

 significantly in polarizability, it is true. You will remember that a hydrocarbon 

 analogue of DDT, was synthesized as a result of the application of just this 

 argument. The substance in which a methyl group is introduced in place of 

 every chlorine atom is used now as an insecticide. It does not go after just the 

 same insects as DDT does, but still it is effective. 



