null (Respiratory enzyme is too broad; use e.g., Cytochrome c oxidase) (null)

A respiratory enzyme refers generally to any member of a group of proteins that catalyze oxidation-reduction reactions during cellular respiration—the process by which cells convert nutrients into usable chemical energy. These include dehydrogenases, reductases, and especially terminal oxidases such as cytochrome c oxidase, which reduce molecular oxygen to water while generating an electrochemical gradient across membranes necessary for ATP synthesis. Most belong structurally to large transmembrane protein complexes containing heme or copper cofactors that facilitate electron transfer from metabolic substrates ultimately onto oxygen. Dysfunction or inhibition leads rapidly to loss of cellular viability due to failure in energy metabolism; thus these proteins are both critical drug targets against pathogens but also pose significant safety risks if inadvertently inhibited in humans.

Other names

Respiratory chain enzymeElectron transport chain enzymeOxidative phosphorylation enzymeTerminal oxidaseCytochrome complex

Drugs typically act by inhibiting electron transfer at key steps in the electron transport chain—blocking oxygen reduction or disrupting proton gradient formation needed for ATP synthesis. Examples: Inhibition of oxygen binding/reduction at terminal oxidases. Disruption of redox cycling within complexes. Some antibiotics exploit differences between bacterial and human respiratory chains for selective toxicity.