MECHANISM OF ANTIBODY FORMATION 121 



specific combining activities with enzymes, and haptenic qualities. 

 Hydrolytic cleavage products which are dialyzable, having molecular 

 weights ranging from 600 to 1,000, exercise serologically specific 

 activities demonstrated by the whole original molecules from which 

 they are derived. 



(c) Antibodies of Vi to Vs size of the original molecule show 

 activities comparable to original activities. Antibodies which proteolyt- 

 ically can be reduced to V2 size with a loss of their species relationship 

 to normal proteins, and antibodies which proteolytically can be 

 changed to such forms that represent loss of their antigenic qualities 

 without loss of their antitoxic activities, show clearly that these bio- 

 logical specificities are inherent in their respective chemical structures. 

 It can therefore be inferred that these specificities arise from specific 

 synthetic enzyme reactions. The summation of the specificities of the 

 smaller structural units represent the various specificities of the whole 

 protein molecule. The concept of the formation of various proteins 

 from proteinogen, as discussed at the beginning of this section, does not 

 appear to be capable of accounting for the above enumerated speci- 

 ficities of structural units. In other words, our view is that the 

 S'pecificity of an antibody molecule is the consequence of Sfecific 

 cellular synthetic 'processes catalyticaily modified hy an antigen to 

 conform with the configuration of certain active groups of the antigenic 

 molecule. 



The change a certain specific protein undergoes from its inactive to 

 its active state, for example, trypsinogen to trypsin, whether by a shift 

 in the pH of the surrounding medium, by an ion effect, by non- 

 specific agents such as concentrated solutions of ammonium or 

 magnesium sulfate, or by the presence of an enzyme to accelerate the 

 spontaneously occurring change, in an autocatalytic manner or other- 

 wise, appear to be a superficial chemical change, and do not involve 

 deep-seated changes to merit the assumption that a new protein is 

 derived from another protein. The enzyme precursor idea does not 

 appear satisfactory as the basis for such fundamental questions pertain- 

 ing to the synthesis of enzymes, antibodies, viruses and the like. The 

 results obtained from immunological and chemical studies appear to 

 contradict the postulate that one protein is autocatalytically formed 

 from another protein, or from a "master proteinogen." 



