MOLECULAR COMPLEMENTARINESS IN ANTIGEN-ANTIBODY SYSTEMS 



11 



TABLE 2 

 Closeness of fit about para position in the /\ 



N 



II 



N 



system 



,0- 



O 



TABLE 3 

 Importance of van der Waals attraction in the — NN 



ASO.3H system 



The relative position of components of a haptenic group is important. This 

 is shown in Table 3, where we have relative constants for the interaction of 

 various substances with anti-^ara-azobenzenearsonate antibodies. It can be 

 seen that it is very important for the benzene ring to be right next to the ar- 

 senate group, since separating the benzene from the arsonate by the CH2 group, 

 as in the case of benzylarsonate, decreases the combining constant markedly. 

 This indicates that the fit of the antibody around the hapten is so close that 

 the displacement of the ring essentially destroys combining power. The benzene 

 ring is very important here as is shown by the fact that neither the arsonate 

 ion itself nor methylarsonate combines with the antibody. This relation is not 

 unique for the benzenearsonate system but holds also for several other systems, 



