10 IMMUNO-CATALYSIS 



globulin fractions of the serum obtained after the first and subse- 

 quent immunizing courses were hydrolyzed to approximately the same 

 extent by proteolytic enzymes. A certain degree of resistance to pep- 

 sin by diphtheria antitoxin serum is also reported (Pappenheimer and 

 Robinson, 1937). However, since the peptic digestions in these cases 

 were carried out at a pH unfavorable for obtaining maximum pro- 

 teolytic activity, it should not be interpreted that these immune bodies 

 are not of protein nature. It can only mean a relative, rather than an 

 absolute resistance to enzymes in comparison with normal serum 

 globulins under these conditions. 



Conclusions. Chemical analysis of purified antibody preparations 

 and of normal globulins have failed to indicate any differences in the 

 percentage of amino acids and total nitrogen. 



Antibodies produced in rabbits to various antigens have so far been 

 found to be indistinguishable by ultracentrifugal and electrophoretic 

 studies from normal rabbit serum globulin. The antibodies produced in 

 the rabbit seem to have the same isoelectric point as the corresponding 

 y-globulin derived from the normal rabbit. 



How is it then that antibodies, chemically and physico-chemically 

 identical with globulins, are serologically distinct entities? This dif- 

 ference has given rise to various hypotheses, which will be discussed 

 later. It suffices to state at this point that this diflFerence is believed 

 to be due to certain variations in the configuration of normal globulin 

 during its synthesis resulting in the formation of antibodies. 



B. THE ROLE OF CATALYSIS IN CHEMICAL REACTIONS AND 

 ITS BEARING ON THE FORMATION OF ANTIBODIES 



In analyzing the nature of various chemical influences which con- 

 tribute to antibody formation in response to antigenic stimuli we 

 cannot at present formulate the mechanism of the chemical reactions 

 involved, but we can at least determine whether an antigen acts as a 

 reactant forming a part of the final reaction product, or as a catalyst 

 directing the synthesis of antibody globulin. 



Changes in organic and inorganic substances, and changes or varia- 

 tions in the physiological processes of living forms are brought about 

 by chemical influences. No matter how the mechanism of these 

 changes or reactions are formulated they take place according to one 



