Effect of redox potential of the heme on the peroxidase activity of cytochrome b562.

Measurements of peroxidase activities of two site-specific mutants and wild type cytochrome b562 suggest that the enzymatic activity correlates with the redox potential of the metal center. A lower value of the Fe(3+)/Fe(2+) redox potential seems to be important for promoting peroxidase activity of the hemeprotein possibly by stabilization of the high-valent redox intermediate involved in the catalytic function. The results provide an approach towards rational tuning of enzyme function when 'grafted' into a new protein environment.