In Citric acid cycle, which enzyme is inhibited by arsenite-

Ans. is 'b' i.e., a ketoglutarate Dehydrogenase* Arsenite binds to the sulfhydryl group and hence inhibits the activity of enzymes which have lipoamide in the active site* Hence Arsenite inhibits Pyruvate Dehydrogenase and a ketoglutarate dehydrogenase of citric acid cycle* It is an example for non competitive inhibition* Succinate dehydrogenase is inhibited by malonate* Aconitase is inhibited by fluroacetate. It is an example for suicidal inhibition.