INHIBITORS STRUCTURALLY RELATED TO MALONATE 



241 



Traws-l,2-Cyclopentane-dicarboxylate inhibits the succinate dehydroge- 

 nase of Tetrahymena geleii homogenates, around 50% inhibition being ob- 

 served when the inhibitor/substrate ratio is 0.5 (Seaman and Houlihan, 

 1950). On the other hand, in intact cells this substance increases the utili- 

 zation of pyruvate, acetate, and succinate. The uptake of acetate is in- 



I 5 10 50 



(Acetylene - Dicarboxylate) 



Fig. 1-23. Effects of acetylene-dicarboxylate (in milf) 



on the oxidations of p>Tuvate -f malate and succinate 



by rat heart mitochondria. (From Montgomery and 



Webb, 1956 b.) 



creased as much as 50% by ^ra??5-l,2-cyclopentane-dicarboxylate and in 

 its presence succinate is taken up and oxidized whereas succinate does not 

 enter the cells normally. It was postulated that trans-1, 2 cyclopex\':ine- 

 dicarboxylate increases the permeability of the membrane to these sub- 

 strates, possibly by an action on the metabolic systems involved in the 



)5 I 2 5 



( Propone - Tncarboxylote) 



Fig. 1-24. Effect of propane -tricarboxylate (in 



inM) on the oxidation of pyruvate + malate by 



rat heart mitochondria. (From Montgomery and 



Webb, 1956 b.) 



