38 



1. MALONATE 



Table 1-8 

 Inhibitor Constants for Dicarboxylate Ions on Succinate Dehydrogenase 



(c) Oxalacetate. The marked inhibition exerted by this substance was first 

 noted by Das (1937 b) and this has been confirmed on the succinate dehydro- 

 genases from a variety of organisms. It is at present recognized as the most 

 potent succinate dehydrogenase inhibitor among the dicarboxylate ions. 

 The binding of the oxalacetate to the enzyme would appear to be at the 

 active center because the inhibition is competitive with succinate (Pardee 

 and Potter, 1948; Kearney and Singer, 1956; Hellerman et al., 1960), and 

 the presence of oxalacetate on the enzyme protects the active center from 

 various sulfhydryl reagents (Stoppani and Brignone, 1957). The reason for 



