ANTIGENS 



39 



Fig. 3-2. Reactions 

 substances. 



anti-gelatin-arsanilic acid antibody with various 



proteins containing a small percentage of carbohydrate is affected in 

 any way by the presence of the carbohydrate, we are forced to con- 

 clude that the specific antigenic determinants of protein antigens 

 consist of various combinations of amino acids. Anything we can find 

 out about the specificity of peptides might therefore apply also to 

 native proteins. 



Landsteiner prepared /'-aminophenyl compounds containing pep- 

 tides made up of the amino acids glycine and leucine 



NH2 



I 

 HCHCOOH 



CH3 NH2 

 I I 

 CHCH2CHCOOH 



CH3 



Leucine 



Glycine 



in various combinations (Fig. Z-Z). These haptens were diazotized 

 and coupled to protein in the usual way, using one protein for the 

 immunizing antigens and another for the test antigens to avoid 

 complicating cross-reactions due to antibody to the protein part of the 

 antigens. 



The strongest precipitation was obtained with the homologous anti- 

 gen (Table 3-1), but cross-reactions were also obtained, generally 

 strongest when the terminal amino acid of the peptide in the test 

 antigen was the same as that in the immunizing antigen. Since these 



