NADH-coenzyme Q oxidoreductase

The first condition is met by having a series of four protein complexes, inserted into the mitochondrial inner membrane, each made up of a number of electron (and sometimes proton) acceptors of increasing redox potential. Three of them (Complexes I, III, and IV) are presented in cartoon form in Figure 5.18. Complex I, referred to more prosaically as NADH-Coenzyme Q oxidoreductase, transfers electrons stepwise from NADH, through a flavo-protein (containing FMN as cofactor) to a series of iron—sulfur clusters (of which more in Chapter 13) and ultimately to coenzyme Q, a lipid-soluble quinone, which transfers its electrons to Complex III. The AE o for the couple NADH/CoQ is 0.36 V, corresponding to a AG° of —69.5 kJ/mol, and in the process of electron transfer, protons are exported into the intermembrane space (between the mitochondrial inner and outer membranes). 

Hodnick WE, Bohmont CW, Capps C, Pardini RS. Inhibition of mitochondrial NADH-oxidase (NADH-Coenzyme Q oxidoreductase) enzyme system by flavonoids a structure-activity study. Biochem Pharmacol 1987 36 2873-2874. Hodnick WE, Duval DL, Pardini RS. Inhibition of mitochondrial respiration and cyanide-stimulated generation of reactive oxygen species by selected flavonoids. Biochem Pharmacol 1994 47 573-580. 

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