164 



IMMUNO-CATALYSIS 



ing configuration different from sucrose, lack affinity for invertase and 

 therefore are not hydrolyzed by invertase and do not inhibit the activity. 



Kuhn (1925) and van Klinkenberg (1932) have further shown that 

 the inhibition of an enzyme by its reaction product is highly specific, 

 and that this specific inhibition is dependent on the configuration of 

 the reaction product in the same manner that the serological specific- 

 ity of the reactions between conjugated sugar-protein antigen and its 

 homologous antibody is dependent on the configuration of the sugar 

 molecule in the antigen. 



Kuhn (1925) determined the inhibitory effect of stereoisomeric 

 carbohydrates on the activity of various amylases. He found that /?- 

 amylase present in malt was inhibited most strongly by )8-maltose. 

 On the other hand a-amylase present in takadiastase (also in pan- 

 creas) was inhibited by a,^-maltose twice as strongly as by i8-maltose. 

 These findings are significant in view of the fact that a-amylase hy- 

 drolyzing starch produces a-maltose and i8-amylase produces ^-malt- 

 ose as a reaction product (starch consists of 36 per cent a-starch and 

 64 per cent /?-starch). These data show that various amylases are most 

 strongly inhibited by those maltoses which they themselves produce 

 specifically. 



The following table is constructed from the results obtained by 

 Kuhn which show clearly that strong inhibition is caused by i8-malt- 

 ose and yS-glucose in contrast to a negligible inhibitory effect exer- 

 cised by their a-isomers.* 



Table VI 



Inhibition of Malt /3-Amylase hy Stereoisomeric Sugars 

 Per cent Inhibition by: 



^The 5 and 11, etc. pair of figures represent per cent inhibitions calculated 

 from results obtained by Kuhn respectively after 12 and 25-minute reaction 

 periods. 



* Hunter and Downs (1945) reported that the action of arginase upon arginine at 

 pH 8.4 is inhibited by all a-amino acids of the naturally occurring configuration, but 

 not by d-a-amino acids, amino acids having the amino group in other than the 

 o-position, urea, or native proteins. 



