Isolation and amino acid sequence of the 9.5 kDa protein of beef heart ubiquinol:cytochrome c reductase.
The 9.5 kDa protein of beef heart ubiquinol:cytochrome c reductase was isolated by a series of chromatographic steps involving dissociation of the complex by urea and guanidine. A clear distinction between the 9.5 kDa protein and the 9.2 kDa protein described earlier [(1982) J. Biochem. 91, 2077-2085] by SDS-PAGE was only achieved when the electrophoresis was performed according to Schägger et al. [(1985) FEBS Lett. 190, 89-94; (1986) Methods Enzymol. 126, 22] because in this gel system the apparent molecular mass of the 9.5 kDa protein is shifted to 11 kDa. The amino acid sequence was determined by solid-phase Edman degradation of the whole protein up to amino acid residue 80 and of the proteolytic cleavage fragments. The protein consists of 81 amino acid residues; its Mr was calculated to be 9507. Structure predictions have been made from average and sided hydropathy profiles. The 9.5 kDa protein is either bound to the core proteins within a 9.5 kDa-core protein subcomplex or else it aggregates easily with the core proteins during the isolation procedure.
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D014450:Electron Transport Complex III; D007202:Indicators and Reagents; D046911:Macromolecular Substances; D008929:Mitochondria, Heart / Q000201:enzymology*; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000302:isolation & purification*; D010446:Peptide Fragments / Q000032:analysis; D011487:Protein Conformation; D011808:Quinone Reductases / Q000302:isolation & purification*
D007202:Indicators and Reagents; D046911:Macromolecular Substances; D009097:Multienzyme Complexes; D010446:Peptide Fragments; D011808:Quinone Reductases; D014450:Electron Transport Complex III