The toxicity of cyanide is linked mainly to the cessation of aerobic cell metabolism. Cyanide reversibly binds to the ferric ions cytochrome oxidase three within the mitochondria. This effectively halts cellular respiration by blocking the reduction of oxygen to water.

What cyanide inhibits?

The cyanide ion, CN, binds to the iron atom in cytochrome C oxidase in the mitochondria of the cells and acts as an irreversible enzyme inhibitor. This prevents cytochrome C oxidase from doing what it needs to do, which is to send electrons to oxygen in the electron transport chain of aerobic cellular respiration.

What process does cyanide disrupt?

Cyanide poisons the mitochondrial electron transport chain within cells and renders the body unable to derive energy (adenosine triphosphate—ATP) from oxygen. Specifically, it binds to the a3 portion (complex IV) of cytochrome oxidase and prevents cells from using oxygen, causing rapid death.