The reaction between reduced azurin and oxidized cytochrome c peroxidase from Pseudomonas aeruginosa.

The reaction between ferric Pseudomonas cytochrome c peroxidase and reduced azurin was investigated by static titration, rapid scan, and stopped flow techniques as well as circular dichroism measurements. Kinetics of the reduction of the enzyme under pseudo-first order conditions reveals a biphasic logarithmic curve indicating that the reaction between enzyme and azurin is complex and comprises of two reactions, one rapid and a slower one. The relative portion of the fast phase from the overall reaction increases with increasing azurin concentration. Kinetic results can be explained by postulating the presence of two different enzyme forms which are slowly interconvertible. Both enzymatic forms form a complex with reduced azurin. The electron transfer between proteins occurs within the molecular complex of azurin and the peroxidase.