Antimycin A

Antimycin A is a chemical compound produced by streptomyces bacteria.

Uses
It is the active ingredient in Fintrol(R), a chemical piscicide (fish poison) used in fisheries management and in the catfish industry.

It is also used as an antibiotic.

Mechanism
Antimycin A functions by inhibiting the oxidation of ubiquinol in the electron transport chain, ultimately preventing the formation of ATP.

More specifically, Antimycin A binds to the Qi site of Complex III (the enzyme cytochrome c oxidoreductase), in the cytochrome b subunit.

The inhibition of Complex III by Antimycin A result in the formation of large quantities of the toxic free radical, Superoxide.

It has also been found to inhibit the cyclic electron flow within photosynthetic systems along the proposed ferredoxin quinone reductase pathway.

Antimycin blocks the flow of electrons from semiquinone to ubiquinone in the Q-cycle of complex III in oxidative phosphorylation. By doing so it inhibits the electron transport pathway thus preventing the consumption of oxygen (which occurs at Complex IV) and disrupting the proton gradient across the inner membrane. It is the disruption of the proton gradient that prevents the production of ATP as protons are unable to flow through the ATP synthase complex.