DAVID PRESSMAN 



Fig. la 



Fig. 1. Possible orientation of hapten with respect to antigen during antibody 

 formation, a. Extended from surface of antigen, b. Lying flat on surface, c. Lying 

 perpendicular to surface. 



to the tyrosine of an antigen. In the first case (Fig. la), the hapten extends 

 normal to the surface of the protein and an antibody formed against this por- 

 tion of the antigen might have a long invagination, about 12 A long, to accom- 

 modate the hapten. There are two other possible orientations, each with the 

 hapten lying along the surface of the protein. One is with the faces of the ben- 

 zene ring lying flat on the surface of the antigen (Fig. lb) and the other is 

 with the benzene rings lying perpendicular to the antigen surface (Fig. Ic). 

 In the first case, an antibody formed against the haptenic portion of the anti- 



