Redox properties and crystal structures of a D. vulgaris flavodoxin mutant in the monomeric and homodimeric forms

The mutant S64C of the short-chain flavodoxin from Desulfovibrio vulgaris has been designed to introduce an accessible and reactive group on the protein surface. Crystals have been obtained of both the monomeric and homodimeric forms of the protein, with the cofactor FMN in either the oxidized or the one electron-reduced (semiquinone) state, and the structures have been determined to high resolution. The redox properties of the different species have been investigated and the variations observed with respect to wild type have been related to the structural changes induced by the mutation and S–S bridge formation.