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Definition

noun

A membrane enzyme that allows the diffusion of protons (hydrogen ions) through its proton channel component while using the energy released from the proton gradient to produce ATP this time through its synthase domain.

Supplement

This enzyme is present in bacterial cell membrane, in inner mitochondrial membrane, and in thylakoid membrane in chloroplasts.

It consists of two major segments: F_o portion, the transmembrane proton channel and F₁ portion, the synthase domain. The proton channel component allows the diffusion of protons (hydrogen ions) from an area where there are more hydrogen ions to an area where there are less hydrogen ions due to a proton gradient. As the proton (H+ ion) moves down the concentration gradient this moves the enzyme in a spinning motion, which brings ADP and inorganic phosphate together to form a bond, thus creating ATP molecule. The resulting ATP molecule is released so that a new ADP molecule can enter for another phosphorylation.

See also: chemiosmosis