| 4144294 |
Lawford HG, Garland PB: Proton translocation coupled to quinone reduction by reduced nicotinamide--adenine dinucleotide in rat liver and ox heart mitochondria. Biochem J. 1972 Dec;130(4):1029-44.
Measurements were made of the stoicheiometry of proton-translocation coupled to NAD (P) H oxidation by several quinones (duroquinone, ubiquinone (0), ubiquinone (1), ubiquinone (2)) in mitochondria from rat liver and ox heart. Observed stoicheiometries of protons translocated per mol of NADH oxidized (--> H (+)/2e (-) ratios; Mitchell, 1966) ranged from 0.75 (rat liver mitochondria with ubiquinone (1)) to 1.55 (ox heart mitochondria with ubiquinone (1) or ubiquinone (2)). Only the rotenone-sensitive pathway of NADH oxidation by quinone was able to support proton translocation. Correction of the observed --> H (+)/2e (-) ratios for the loss of reducing equivalents to the rotenone-insensitive pathway increased their value to approx. 2.0. It is concluded that the rotenone-sensitive NADH- ubiquinone reductase activity of the respiratory chain may be organized in the mitochondrial membrane as a proton-translocating oxidoreduction loop. The number of such loops between NADH and ubiquinone is one, and not two, as initially proposed by Mitchell (1966). |
6(0,0,1,1) |