Premium
Redox behaviour of the haem domain of flavocytochrome c 3 from Shewanella frigidimarina probed by NMR
Author(s) -
Pessanha Miguel,
Rothery Emma L.,
Louro Ricardo O.,
Turner David L.,
Miles Caroline S.,
Reid Graeme A.,
Chapman Stephen K.,
Xavier António V.,
Salgueiro Carlos A.
Publication year - 2004
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/j.febslet.2004.10.098
Subject(s) - chemistry , flavin adenine dinucleotide , flavin group , redox , ligand (biochemistry) , periplasmic space , shewanella oneidensis , electron transfer , crystallography , heme , ferredoxin , cofactor , biochemistry , inorganic chemistry , enzyme , escherichia coli , biology , genetics , receptor , bacteria , gene
Flavocytochrome c 3 from Shewanella frigidimarina (fcc 3 ) is a tetrahaem periplasmic protein of 64 kDa with fumarate reductase activity. This work reports the first example of NMR techniques applied to the assignment of the thermodynamic order of oxidation of the four individual haems for such large protein, expanding its applicability to a wide range of proteins. NMR data from partially and fully oxidised samples of fcc 3 and a mutated protein with an axial ligand of haem IV replaced by alanine were compared with calculated chemical shifts, allowing the structural assignment of the signals and the unequivocal determination of the order of oxidation of the haems. As oxidation progresses the fcc 3 haem domain is polarised, with haems I and II much more oxidised than haems III and IV, haem IV being the most reduced. Thus, during catalysis as an electron is taken by the flavin adenosine dinucleotide from haem IV, haem III is eager to re‐reduce haem IV, allowing the transfer of two electrons to the active site.