Cyanide is an irreversible inhibitor of the enzyme cytochrome c oxidase in the fourth complex in the membrane of the mitochondria of cells. It attaches to the iron within this protein. The binding of cyanide to this cytochrome prevents transport of electrons from cytochrome c oxidase to oxygen. As a result, the electron transport chain is disrupted, meaning that the cell can no longer aerobically produce ATP for energy. Tissues that mainly depend on aerobic respiration, such as the central nervous system and the heart, are particularly affected. Antidotes to cyanide poisoning include hydroxocobalamin and sodium nitrite which release the cyanide from the cytochrome system, and rhodanase, which is an enzyme occurring naturally in mammals that combines serum cyanide with thiosulfate, producing comparatively harmless thiocyanate
.July 01, 2008
