<prompt> Uncoupler of oxidative phosphorylation is2, 4-DNPBALTTFARotenone  <response>: Mechanism of Action of DNP as uncoupler Dinitrophenol DNP a potent uncoupler is amphipathic and increase the permeability of the lipoid inner mitochondrial membrane to protons H, thus reducing the electrochemical potential and sho-circuiting the ATP synthase. In this way, oxidation can proceed without phosphorylation. Note: DNP was used for weight loss. But it was discontinued due to hypehermia and other side effects Inhibitors of ETC Site-I Complex-I Rotenone: A fish poison and also insecticide. Inhibits transfer of electrons through complex-I-NADH-Q-reductase. Amobarbital Amytal and Secobarbital: Inhibits electron transfer through NADH-Q reductase. Piericidin A: An antibiotic. Blocks electron transfer by competing with CoQ. Drugs: Chlorpromazine and hypotensive drug like guanethidine. Site-II Complex III Antimycin A BAL dimercaprol Hypoglycaemic drugs: like Phenformin Site-III Complex IV Cyanide Blocks electron transfer from cyt b to c1 Inhibits terminal H2S Azide transfer of electrons to molecular O2 Co Carbon monoxide: Inhibits Cyt. oxidase by combining with O2 binding site. It can be reversed by illumination with light. Complex II: Succinate dehydrogenase FAD Carboxin TTFA Specifically inhibit transfer of reducing equivalent from succinate dehydrogenase Malonate: A competitive inhibitor of succinate dehydrogenase.Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th edition, page no: 143 146 