Antimycin A
Antimycins are a group of secondary metabolites produced by Streptomyces
Streptomyces is the largest genus of Actinobacteria and the type genus of the family Streptomycetaceae. Over 500 species of Streptomyces bacteria have been described. As with the other Actinobacteria, streptomycetes are gram-positive, and have genomes with high guanine and cytosine content...



It is the active ingredient in Fintrol, a chemical piscicide
A piscicide is a chemical substance which is poisonous to fish. The primary use for piscicides is to eliminate a dominant species of fish in a body of water, as the first step in attempting to populate the body of water with a different fish...

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

In the context of biology, poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism....

) used in fisheries management and in the catfish
Catfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...


Mechanism of action

Antimycin A binds to the Qi site of cytochrome c reductase
Coenzyme Q – cytochrome c reductase
In enzymology, a ubiquinol—cytochrome-c reductase is an enzyme that catalyzes the chemical reactionThus, the two substrates of this enzyme are dihydroquinone and ferri- cytochrome c, whereas its 3 products are quinone , ferro- cytochrome c, and H+.This enzyme belongs to the family of...

, thereby inhibiting the oxidation of ubiquinol
Ubiquinol is an electron-rich form of coenzyme Q10.The natural ubiquinol form of coenzyme Q10 is 2,3-dimethoxy-5-methyl-6-poly prenyl-1,4-benzoquinol, where the polyprenylated side chain is 9-10 units long in mammals...

 in the electron transport chain
Electron transport chain
An electron transport chain couples electron transfer between an electron donor and an electron acceptor with the transfer of H+ ions across a membrane. The resulting electrochemical proton gradient is used to generate chemical energy in the form of adenosine triphosphate...

 of oxidative phosphorylation. The inhibition of this reaction disrupts the formation of the proton gradient
Electrochemical gradient
An electrochemical gradient is a spatial variation of both electrical potential and chemical concentration across a membrane; that is, a combination of the membrane potential and the pH gradient...

 across the inner membrane
Inner mitochondrial membrane
The mitochondrial inner membrane forms internal compartments known as cristae, which allow greater space for the proteins such as cytochromes to function properly and efficiently. The electron transport chain is located on the inner membrane of the mitochondria...

. The production of ATP is subsequently inhibited, as protons are unable to flow through the ATP synthase complex in the absence of a proton gradient. This inhibition also results in the formation of quantities of the toxic free radical superoxide
A superoxide, also known by the obsolete name hyperoxide, is a compound that possesses the superoxide anion with the chemical formula O2−. The systematic name of the anion is dioxide. It is important as the product of the one-electron reduction of dioxygen O2, which occurs widely in nature...


It has also been found to inhibit the cyclic electron flow within photosynthetic
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...

 systems along the proposed ferredoxin
Ferredoxins are iron-sulfur proteins that mediate electron transfer in a range of metabolic reactions. The term "ferredoxin" was coined by D.C. Wharton of the DuPont Co...

quinone reductase pathway.

Fungus-growing attine ants have been shown to use antimycins - produced by symbiotic Streptomyces bacteria - in their fungiculture, to inhibit non-cultivar (i.e. pathogenic) fungi. One research group studying these symbiotic Streptomyces bacteria recently identified the biosynthetic gene cluster for antimycins, which was unknown despite the compounds themselves being identified 60 years ago. Antimycins are synthesised by a hybrid polyketide synthase (PKS)/non-ribosomal peptide synthase (NRPS).
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