An NMR study of the redox dependent changes in putidaredoxin, a 2Fe-2S electron transfer protein

lectron transfer reactions in biological systems are of crucial importance for the energy metabolism of living systems. Putidaredoxin (Pdx) is a 106 amino acid electron transfer protein containing a 2Fe-2S cluster as the prosthetic group. It functions as an electron shuttle between cytochrome P-450;Structural calculations were done using NOE and dihedral angle constraints obtained from NMR spectroscopy to determine the 3D structure of oxidised Pdx. The hyperfine shifted resonances of oxidised and reduced Pdx have been characterised and the shifts of the oxidised form are found to resemble those of the vertebrate ferredoxins. The conformational changes upon reduction have been characterised. Increased unpaired electron spin density on the metal cluster in reduced relative to oxidized Pdx increases the number of...