Isolation and reconstitution of the iron-sulfur protein in ubiquinol-cytochrome c oxidoreductase complex. Phospholipids are essential for the integration of the iron-sulfur protein in the complex.
An iron-sulfur protein has been purified from beef heart ubiquinol-cytochrome c oxidoreductase (Complex III) of the mitochondrial respiratory chain by phenyl-Sepharose column chromatography and Sephacryl S-200 gel chromatography. Depletion of most of the endogenous phospholipids in the complex was a prerequisite to the dissociation of the protein from the complex in the former chromatography. The iron-sulfur protein was nearly homogeneous as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and contained 76 ng atoms of nonheme iron and 66 nmol of acid-labile sulfide/mg of protein. When this preparation was incubated with an iron-sulfur protein-depleted complex in the presence of soybean phospholipids, the enzymic activity was restored up to 90% of that of the parent Complex III, whereas the recovery of the activity was marginal in the absence of the phospholipids. Thus it is clear that the iron-sulfur protein is integrated into the complex with the aid of phospholipids.
D000818:Animals; D002417:Cattle; D002850:Chromatography, Gel; D014450:Electron Transport Complex III; D004591:Electrophoresis, Polyacrylamide Gel; D007506:Iron-Sulfur Proteins / Q000032:analysis*; D008667:Metalloproteins / Q000032:analysis*; D008929:Mitochondria, Heart / Q000201:enzymology; D009097:Multienzyme Complexes / Q000302:isolation & purification*; D009247:NADH, NADPH Oxidoreductases / Q000302:isolation & purification*; D010743:Phospholipids / Q000032:analysis*; D011808:Quinone Reductases / Q000302:isolation & purification*
D007506:Iron-Sulfur Proteins; D008667:Metalloproteins; D009097:Multienzyme Complexes; D010743:Phospholipids; D009247:NADH, NADPH Oxidoreductases; D011808:Quinone Reductases; D014450:Electron Transport Complex III