MOLECULAR COMPLEMENTARINESS IN ANTIGEN-ANTIBODY SYSTEMS / 



1700 



950 



Fig. 4. Van der Waals outline of inhibiting liapten superimposed on outline of 

 an injected hapten group. Numerical values are for AF(relative). (Reproduced from 

 the Journal of the American Chemical Society, 76, 6339 (1954) with permission of 

 the Editor.) 



There are listed the free energies of combination of these substances with 

 homologous antisera relative to the combination of the unsubstituted benzoate 

 ion. You can see that, depending on which position the chlorine occupies, there 

 is a steric interaction which contributes to the decreased interaction of these 

 substances with the specific antibodies. 



The free energies involved when the chlorine is in the various positions are 

 summarized in Fig. 5. 



In the case of the antibody against the wc/a-azobenzoate group, we find 

 that there is a large effect of a chlorine in either of the orlho positions. There 

 are two possible reasons for this large effect. There may be a steric effect of 

 the chlorine in interfering with the combination of the antibody or there may 

 be an effect of the o-chlorine to tilt the carboxylate ion out of the plane of the 



