ANTIBODY AS A SPECIFIC ENZYME INHIBITOR 151 



2. Specificity of Enzymes Which Catalyze Stereoisomeric 

 Substrates 



The above cited facts may be considered some of the most striking 

 examples as characteristic of the role of determinant groups in general, 

 and for the highly specific influence of the spatial configuration of 

 glucosides in particular, on the specificity of immune reactions. These 

 findings have shown beyond doubt the sensitivity of the response of 

 the cytoplasm-antigen vi^hich is involved in the synthesis of the immune 

 globulins. These facts have no doubt been instrumental in the emphasis 

 of the oft referred analogy betu^een immune and enzyme reactions. 

 This analogy is clearly shown in the animal system which demonstrates 

 enzyme specificity in the synthesis of a particular optical isomer as well 

 as in the production of specific antibodies against optical antipodes. 

 The analogy between these two types of biocatalytic reactions offers 

 indeed a very attractive prospect of comparing directly the role of 

 the participants in immune reactions wdth those of enzyme reactions. 



In comparison with the role of the stereochemical and optical con- 

 figuration of the carbohydrate groups of the synthetic gluco-protein 

 antigens on the specificity of antibodies, we will discuss below the 

 specificity of carbohydrases. According to the specificity theory of 

 Weidenhagen (1932, 1940) the specificity of carbohydrases is char- 

 acterized by their ability to hydrolyze or catalyze carbohydrates of 

 three structural types. They are: 



a. Sugar Isomerism, that is, the sugars differing at C-atoms. For 

 example, the difference between glucose and galactose at the fourth 

 carbon-atom; 



b. Constitutional Isomerism, that is, the isomerism between aldoses 

 and ketoses. For example, the difference between glucose and fructose; 



c. Ring Isomerism, or a- and ^S-isomerism. 



For discussion of the possible analogy between the specificity of the 

 glycoside— azoprotein antigens and the specificity of the carbohydrases 

 which hydrolyze di- and tri-saccharides, the following table is con- 

 structed. 



Table IV shows that a disaccharide such as saccharose containing 

 a- and )8-hexosides are hydrolyzed by both the a- and )8-glucosidases. 

 Each glucosidase can attack, however, only one of the linkages and 



