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Isolation and amino acid sequence of the 9.5 kDa protein of beef heart ubiquinol:cytochrome c reductase
Author(s) -
Borchart U.,
Machleidt W.,
Schägger H.,
Link T.A.,
von Jagow G.
Publication year - 1986
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(86)80515-4
Subject(s) - edman degradation , biochemistry , peptide sequence , amino acid , chemistry , protein primary structure , cytochrome , gel electrophoresis , molecular mass , reductase , cytochrome c , ubiquinol , biology , enzyme , coenzyme q – cytochrome c reductase , mitochondrion , gene
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 M r 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.