FIGURE 11.
Maximum rates of superoxide/H2O2 production from characterized sites of the mitochondrial respiratory chain. The components of the NADH/NAD+ isopotential group are: OF, flavin site of 2-oxoglutarate dehydrogenase; BF, flavin site of branched-chain 2-oxoacid dehydrogenase; PF, flavin site of pyruvate dehydrogenase; IF, flavin site of complex I. The ubiquinone binding site of complex I (site IQ) is between isopotential groups. The components of the QH2/Q isopotential group are: IIF, flavin site of complex II; GQ, quinone site of mitochondrial glycerol-3-phosphate dehydrogenase; EF, flavin site of the electron transferring flavoprotein/ETF:ubiquinone oxidoreductase system; IIIQo, Qo binding site of complex III. All data were mathematically corrected for matrix peroxidase activity using the 1-chloro-2,4-dinitrobenzene correction described under “Experimental Procedures.” Data for OF, BF, PF, and IF are from Figs. 5C, 7C, 9C, and 2D (plus aspartate/ATP); other sites are replotted from (16). The maximum rates from OF, BF, and PF were corrected by subtracting the rate from site IF at the same NAD(P)H reduction level. Data are the means ± S.E. (n ≥ 3).