Structural and kinetic studies of the pyruvate-ferredoxin oxidoreductase/ferredoxin complex from Desulfovibrio africanus.

摘要: The pyruvate–ferredoxin oxidoreductase (PFOR)/ferredoxin (Fd) system of Desulfovibrio africanus has been investigated with the aim understanding more fully protein–protein interaction and kinetic characteristics electron transfer between two redox partners. D. africanus contains three Fds (Fd I, Fd II Fd III) able to function as acceptors for PFOR. complete amino acid sequence was determined by automatic Edman degradation. It revealed a striking similarity that Fd I. protein consists 64 residues its is in agreement molecular mass 6822.5 Da measured electrospray MS. five cysteine which first four (Cys11, Cys14, Cys17 Cys54) are likely ligands single [4Fe–4S] cluster. A covalently cross-linked complex PFOR Fd I or obtained using water soluble carbodiimide. This exhibited stoichiometry one ferredoxin subunit dependent on ionic strength. second-order rate constants electrochemically cyclic voltammetry 7 × 107 m−1·s−1 2 × 107 m−1·s−1 Fd III. Km values both electrochemical spectrophotometric method have found be 3 µm 5 µm, respectively. three-dimensional modelling surface analysis Fd I, suggest formed aspartic acid/glutamic invariant lysine surrounding distal cluster All these studies indicative involvement electrostatic interactions