ANTIBODY AS A SPECIFIC ENZYME INHIBITOR 149 



These hexosides were diazotized and coupled, respectively, with 

 horse serum globulin and crystalline egg albumin. 



Gluco-globulin antiserum prepared by the immunization of rabbits 

 reacted not only with gluco-globulin but also with gluco-albumin. 

 Anti-serum reactive with gluco-albumin showed no reaction with 

 galacto-albumin. The serum of rabbits immunized with galacto- 

 globulin reacted with the solutions of galacto-globulin and galacto- 

 albumin in approximately equal titre. These antibodies, however, failed 

 to precipitate gluco-albumin. These data provided proof that the con- 

 figuration of the sugar radical, regardless of the nature of the protein 

 to which it was attached, was a determining factor in the serological 

 specificity of these conjugated antigens. 



The antisera prepared with sugar proteins also contained anti- 

 protein antibodies which exhibited the protein specificity of the species 

 from which they were derived. They could be removed from the 

 immune sera by specific absorption without loss in the titre of the 

 coexisting anti-carbohydrate antibodies. Conversely, the anti-carbo- 

 hydrate antibodies could be specifically inhibited from reacting by the 

 addition of the homologous glucoside without diminishing the activity 

 of the anti-protein precipitins present in the same serum. 



Avery, Goebel and Babers (1932) also showed that, though the 

 antisera against azo-proteins of p-aminophenol-a-glucoside cross-reacted 

 with i8-antigen, a differentiation in the specificity of a- and /^-antigens 

 could be affected by cross-inhibiting tests. The reaction of an immune 

 serum with its homologous antigen was specifically inhibited only by 

 the homologous glucoside, while the cross-reaction between this serum 

 and the heterologous antigen was completely inhibited by either gluco- 

 side. This lack of reciprocal inhibition of the precipitins in a- and 13- 

 antisera was interpreted, by the authors, as further evidence of the 

 lack of the immunological identity of the two isomeric glucosides. 



In studies with azo-proteins of a-maltoside, ^-cellobioside, i8-lacto- 

 side and /?-gentiobioside, Goebel, Avery and Babers (1934) demon- 

 strated that the specificity of serological cross-reactions of disaccharide 

 antigens is determined by the stereochemical configuration of the 

 terminal hexose molecule; that only the test antigen containing the 

 maltoside (terminal hexose, a-glucose*) reacted only in a-antiserum. 



* Strictly speaking the terminal hexoses in the above disaccharides are no longer free 

 molecules and therefore should be named hexosides. 



