Measurement of the oxidation-reduction potentials for one-electron and two-electron reduction of electron-transfer flavoprotein from pig liver.
Potentiometric titrations of pig liver electron-transfer flavoprotein (ETF) were performed at pH 7.5 and 4 degrees C, both in the reductive and oxidative directions. Reduction of ETF to the hydroquinone form required a total of two reducing equivalents/mol of ETF with the formation of sub-stoichiometric amounts of anionic semiquinone as an intermediate. The oxidation-reduction potentials for the two one-electron couples, oxidized ETF/ETF semiquinone and ETF semiquinone/fully reduced ETF, are +4 mV and -50 mV respectively. The overall midpoint potential for the two-electron couple (oxidized ETF/fully reduced ETF) is -23 mV.
D000818:Animals; D004579:Electron Transport; D044927:Electron-Transferring Flavoproteins; D005420:Flavoproteins; D008930:Mitochondria, Liver / Q000032:analysis*; D010084:Oxidation-Reduction; D011199:Potentiometry; D011809:Quinones; D013552:Swine
D044927:Electron-Transferring Flavoproteins; D005420:Flavoproteins; D011809:Quinones