Purification and characterization of cytochrome c from Neisseria meningitidis

Abstract Cytochrome c , a c-type cytochrome with unique spectroscopic and magnetic properties, has been characterized in a variety of denitrifying and photosynthetic bacteria. Cytochrome c has a role in defence and/or removal of NO but the mechanism of action is not clear. To examine the function of cytochrome c from Neisseria meningitidis, the protein was purified after heterologous overexpression in Escherichia coli. The electronic spectra of the oxidized c demonstrated a pH-dependent transition (over the pH range of 6-10) typical of known c -type cytochromes. Interestingly, the form in which NO is supplied determines the redox state of the resultant haem-nitrosyl complex. Fe(III)-NO complexes were formed when Fe(II) or Fe(III) cytochrome c was sparged with NO gas, whereas an Fe(II)-NO complex was generated when NO was supplied using DEA NONOate (diazeniumdiolate)