Rotenone and Amytal

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Cyanide, Carbon Monoxide, and Azide
Antimycin A
Overview of Respiratory Inhibitors

Inhibitors cause a block in the pathway at the crossover point - the specific target of inhibition when an overall pathway is blocked. Rotenone and amytal block NADH dehydrogenase (complex 1) in the respiratory chain, blocking the flow of electrons from NADH to CoQ. Therefore no ATP is formed from NADH, but two ATPs are formed per FADH₂.

Amytal (5-ethyl-5-isoamylbarbituric acid) was one of the first inhibitors of Site 1 to be found. The site of inhibition of amytal has been localized on the ubiquinone side of the flavoprotein segment of NADH dehydrogenase. Hatefi (1968) places the site at the point of electron transfer from the FMN flavoprotein to the group of Fe-S proteins. (Please also see p.523 of our textbook for a graphical depiction). The mechanism by which amytal inhibits electron transfer is unclear.

Amytal, also known as amobarbital or blue heavens, is a barbiturate, and is occasionally used to treat insomnia, tension, and anxiety disorders. Doctors also sometimes prescribe barbiturates for the nerve disorder known as epilepsy .

Rotenone also blocks NADH dehydrogenase (complex 1) in the respiratory chain. The nature of the binding site is still unclear. Bois and Estabrook (1969) provided early evidence that the site was a Fe-S protein. Rotenone, also known as derris dust and deretox) is an organic insecticide derived from derris root, which is grown in Malaya. Rotenone is used in home gardens for insect control, for lice and tick control on pets, and for fish eradication as part of water body management. Human health hazards include the fact that is it a suspected gastrointestinal or liver toxicant as well as a respiratory toxicant Local effects on the body include conjunctivitis, dermatitis, sore throat, and congestion. Ingestion produces effects ranging from mild irritation to vomiting. Inhalation of high doses can cause increased respiration followed by depression and convulsions

Bioenergetics Quiz!

Electron Transport Chain

Electron Transport Chain Complexes

Decreased rotenone sensitivity of mitochondrial NADH Coenzyme Q reductase in platelets from old individuals

B.O.B.'s Glycolysis, Krebs Cycle, and Electron Transport Chain Pages