ANTI-ENZYME IMMUNITY 207 



antibody would not appear to be due to an in vivo blocking of the 

 antigenic groups from exercising their activity. There seems, therefore, 

 to exist a striking interrelationship between the specific combining 

 abilities of antigens and their catalytic activities. There is, however, the 

 fact that when an antigen is proteolytically reduced to split prod- 

 ucts the enzymic and antigenic properties are lost without parallel 

 loss of combining abilities. The split products merely function as hap- 

 tens. Here again, the point to be remembered is that the catalytic ac- 

 tivity of the intact molecule is the principal factor which enables its 

 potential haptenic groups to invoke complementary parts in the anti- 

 body molecule during its synthesis. 



The interrelationships cited do not appear to account for the loss 

 of enzyme (or toxic) activity without loss of the ability to produce 

 neutralizing antibody when the toxin or enzyme is treated with non- 

 specific agents such as ketene or formaldehyde. This discrepancy would 

 seem to be more apparent than real. The following possibilities can 

 be considered to account for this discrepancy: 



First; The neutralization of the enzyme or toxic activity of a protein 

 by its specific antibody may be a secondary effect related to the union 

 of the protein as antigen with the antibody which has been produced 

 in response to the inactivated but antigenic protein. If formaldehyde, 

 ketene etc., can cause inactivations, one could postulate that inactiva- 

 tion of the enzyme and toxic properties would automatically result 

 when the antigen-antibody combining reaction occurs. Such combina- 

 tions produce neutralization of the respective negative and positive 

 charges, and a decrease in the energy content of the reactive groups. 

 Consequently, possible deleterious effects on other regions of the 

 active protein molecules might transform the enzyme molecule into 

 an inactive form in the combined state.* There are no experimental 

 data to support or to refute such an interpretation of the observed 

 effect. The discussed properties are so interrelated that it is difficult 

 to characterize which is cause, which is effect. As in the oxidation 

 of SH groups, or the reduction of -S-S- groups resulting in the 



^Stanley (1936) reported that the precipitation reaction, which has been used 

 as a measure of virus activity, may not be used unreservedly for this purpose. 



Kassanis (1943) reported that normal and heterologous sera cause marked neutral- 

 ization of plant viruses— tobacco mosaic virus, tomato bushy stunt virus and two 

 cultures of tobacco necrosis viruses. The additional specific effect of homologous 

 antisera was small in comparison. Unless sera were kept frozen their non-specific neu- 



