Molecular identification of the ten subunits of cytochrome-c reductase from potato mitochondria.
Cytochrome-c reductase (EC 1.10.2.2.) from Solanum tuberosum L. comprises ten subunits with apparent molecular sizes of 55, 53, 51, 35, 33, 25, 14, 12, 11 and 10 kDa on 14% SDS-PAGE. The identity of the subunits was analysed by direct amino-acid sequencing via cyclic Edman degradation. A large-scale purification procedure for the enzyme complex based on affinity chromatography and gelfiltraton is described. All subunits were enzymatically fragmented and the generated peptides were separated by reverse-phase HPLC. Complete or partial sequence determination of 33 peptides comprising a total of nearly 500 amino acids showed, that cytochrome-c reductase from potato contains three respiratory proteins (cytochrome b, cytochrome c1, and the "Rieske" iron-sulfur protein), four small proteins with molecular sizes below 15 kDa (so-called Q-binding, hinge, cytochrome-c1-linked and core-linked proteins) and three proteins in the 50-kDa range which show similarity to members of the core/PEP/MPP protein family (core/processing enhancing protein/mitochondrial processing peptidase). In fact these subunits show highest sequence identity either to MPP or PEP, which is in line with earlier findings, that isolated cytochrome-c reductase from potato exhibits processing activity towards mitochondrial precursor proteins.
Braun
H P
HP
Institut für Genbiologische Forschung Berlin GmbH, Germany.
Kruft
V
V
Schmitz
U K
UK
D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D009245:NADH Dehydrogenase / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D011198:Solanum tuberosum / Q000201:enzymology*
D010446:Peptide Fragments; D009245:NADH Dehydrogenase