Effects of Inhibitors on the Membrane Potential (Δψ) of Mung Bean Mitochondria
Safranine O was used to measure changes imposed on the membrane potential (Δψ) of mung bean mitochondria by different metabolic conditions and inhibitors. Changes in Δψ were correlated with simultaneously made measurements of O2 uptake. Δψ values of 129 ± 3 mV and 144 ± 4 mV were obtained under state 3 and state 4 conditions, respectively, during the oxidation of malate. At concentrations of electron transport inhibitors that maximally inhibited O2 utilization, Δψ was only partially collapsed. Under state 4 conditions, the collapse of Δψ to the Donnan potential by uncouplers correlated with the concentration at which state 4 respiration was stimulated maximally. Inhibition of O2 utilization by F0 inhibitors correlated with an increase in Δψ from the state 3 to the state 4 potential.
KeywordsAcetone Respiration MgCl NADH Mannitol
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