CHEMICAL CONSTITUENTS 263 



charides which may be found to possess similar chemical and im- 

 munological relationships to those of Pneumococcus but their ex- 

 istence in no way detracts from the soundness of our present 

 serological classification of pneumococci. Tempting as it is, fur- 

 ther discussion of the immunological significance of the carbohy- 

 drates from sources other than Pneumococcus would not be per- 

 tinent to the present subject. 



FUNCTION OF SUGARS IN DETERMINING ANTIGENIC SPECIFICITY 

 AND CONJUGATED PROTEINS 



The newly discovered and highly important function of sugars 

 in determining the antigenic specificity of conjugated proteins was 

 studied by Goebel, Avery, and Tillett. The two first-named au- 

 thors, 521 aiming to gain more exact information concerning this 

 specific action of carbohydrates, set about building two isomeric 

 carbohydrate-protein compounds. They first synthesized p-amino- 

 phenol (3-glucoside and p-aminophenol (3-galactoside and then cou- 

 pled these hexosides with the globulin from horse serum. The two 

 protein-sugar complexes thus obtained differed only in the carbo- 

 hydrate radical of each and in the spatial configuration of the H 

 and OH groups by a single carbon atom. In a second paper Avery 

 and Goebel, 44 after coupling the diazophenol glucosides to crystal- 

 line egg albumin in addition to serum globulin, studied the im- 

 munological behavior of the preparations. When two chemically 

 different carbohydrate derivatives were bound to the same protein, 

 the newly formed antigens exhibited distinct immunological speci- 

 ficity. When the same carbohydrate radical was conjugated with 

 two chemically different and serologically distinct proteins, both 

 of the sugar-proteins thus formed acquired a common serological 

 specificity. Therefore, simple differences in the molecular configu- 

 ration of the two isomers — glucose and galactose — sufficed to 

 orient specificity when the corresponding glucosides were coupled 

 to the same protein. The unconjugated glucosides, although them- 

 selves not precipitable in immune serum, specifically inhibited the 



