Novel isolation and reconstitution of the iron-sulfur protein of mitochondrial Complex III.
An iron-sulfur protein was isolated from mitochondrial Complex III as a single band on SDS-polyacrylamide gel electrophoresis by hydrophobic interaction chromatography, in which the complex was dissociated into the iron-sulfur protein and the rest of the complex with a loss of enzymic activity. The critical condition for the dissociation was depletion of boundary phospholipids to 0.6% (w/w). After gel filtration of the isolated iron-sulfur protein, 76 ng atom of non-heme iron and 66 nmol of acid-labile sulfide were found per mg of the protein. By incubating the protein with the iron-sulfur protein depleted-complex in the presence of a soybean phospholipid mixture, the enzymic activity was fully recovered. The electrophoretic pattern of the reconstituted complex showed a polypeptide composition similar to that of the original Complex III. These results indicate that the iron-sulfur protein is attached in the complex with the aid of boundary phospholipids.
D000818:Animals; D002417:Cattle; D014450:Electron Transport Complex III; D004591:Electrophoresis, Polyacrylamide Gel; D007506:Iron-Sulfur Proteins / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008667:Metalloproteins / Q000302:isolation & purification*; D008929:Mitochondria, Heart / Q000201:enzymology*; D009097:Multienzyme Complexes / Q000302:isolation & purification* / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000302:isolation & purification*; D010743:Phospholipids / Q000032:analysis; D011808:Quinone Reductases / Q000302:isolation & purification* / Q000378:metabolism
D007506:Iron-Sulfur Proteins; D008667:Metalloproteins; D009097:Multienzyme Complexes; D010743:Phospholipids; D009247:NADH, NADPH Oxidoreductases; D011808:Quinone Reductases; D014450:Electron Transport Complex III