The mechanism of uncoupling of oxidative phosphorylation by 2,4-dinitrophenol.

2,4-Dinitrophenol fails to stimulate the breakdown of the soluble high energy intermediate of oxidative phosphorylation isolated from Alcaligenes faecalis extracts. Once the intermediate is broken down, by other reactions, the coupling enzyme is prevented from reassociation with the electron transport particles by 2,4-dinitrophenol. Phosphorylating particles washed with 2,4-dinitrophenol lose coupling enzyme and with it the ability to form the energy-rich intermediate and to couple phosphorylation to electron transport. Phosphorylating particles containing bound coupling enzyme are able to form the high energy intermediate even in the presence of 2,4-dinitrophenol. However, after this first cycle of formation, no more can be formed because 2,4-dinitrophenol prevents the reassociation of coupling enzyme with the electron transport particles. 2,4-Dinitrophenol stimulates respiration in the bacterial phosphorylating particles.