The kinetic mechanism(s) of cytochrome oxidase. Techniques for their analysis and criteria for their validation.

The steady-state kinetics of cytochrome oxidase exhibit two characteristics that impose severe constraints on any proposed mechanism. The first is the exponential consumption of ferrocytochrome c and the second is the nonhyperbolic dependence of reaction velocity upon the concentration of cytochrome c. Because the reaction mechanism contains at least five, and possibly six, substrates, realistic mechanisms can be very complex and not suitable for analysis by conventional means. We have developed procedures for rapidly establishing whether a postulated mechanism will exhibit the necessary behavior and for calculating the steady-state activity that will result for any mechanism, given values for the individual rate constants and reactant concentrations. The procedures have been used with mechanisms containing up to 40 enzyme species.