DCCD sensitivity of electron and proton transfer by NADH: ubiquinone oxidoreductase in bovine heart submitochondrial particles--a thermodynamic approach.
The sensitivity of the H+/2e- ratio of the redox-driven proton pumping by the NADH: ubiquinone reductase (complex I) of the submitochondrial particles to dicyclohexylcarbodiimide (DCCD) was studied by a thermodynamic approach, measuring the membrane potential and delta pH across the membrane and the redox potential difference across the complex I span of the respiratory chain. The delta Gr/delta muH+ ratio did not decrease upon additions of 50 or 100 nmol of DCCD per mg protein in the presence of oligomycin although the H+/2e- ratio has been demonstrated to decrease upon DCCD addition in kinetic experiments with mitochondria. Complex I then becomes reminiscent of the cytochrome bc1 complex, which shows DCCD sensitivity of the kinetically but not thermodynamically determined H+/2e- ratio.
Vuokila
P T
PT
Department of Medical Biochemistry, University of Oulu, Finland.
Hassinen
I E
IE
D000818:Animals; D002234:Carbodiimides / Q000494:pharmacology*; D002417:Cattle; D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology*; D004579:Electron Transport / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008564:Membrane Potentials; D008929:Mitochondria, Heart / Q000201:enzymology* / Q000648:ultrastructure; D016660:NAD(P)H Dehydrogenase (Quinone); D009840:Oligomycins / Q000494:pharmacology; D010084:Oxidation-Reduction; D011522:Protons; D011808:Quinone Reductases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013367:Submitochondrial Particles / Q000201:enzymology*; D013816:Thermodynamics
D002234:Carbodiimides; D009840:Oligomycins; D011522:Protons; D004024:Dicyclohexylcarbodiimide; D016660:NAD(P)H Dehydrogenase (Quinone); D011808:Quinone Reductases