Energy-linked conformational change of the mitochondrial membrane measured with the NH 2-modifying reagent, acrolein

Abstract

Application of the NH 2-modifying reagent, acrolein (2-propenal, CH 2 = CHCHO), to the mitochondrial membrane gave the information that amino groups in the mitochondrial membrane in the energized state are more accessible to acrolein than those in the non-energized state. This finding was supported by the following experimental results. Addition of acrolein to the respiring mitochondria gives rise to rapid H + production, which is caused by the reaction of the amino groups in the membrane with acrolein, followed by a slow H + consumption, whereas resting mitochondria produce little H +. The H + production is stopped by the addition of NaN 3, antimycin A and 2-thenoyltrifluoroacetone but not by oligomycin. During the course of H + production, O 2 consumption and Ca 2+ uptake remain completely active, indicating that mitochondrial function is unaffected. The subsequent H + consumption may be closely related to the destruction of the transmembrane proton gradient formed by mitochondrial respiration.