Toni,
>I have a vague idea that heterogeneous kinetics look quite a bit
>different from our regular solution-based kinetics. I've always
>presumed heterogeneous kinetics would apply in the situation you
>describe. Are you say they simply differ in the units? Or am I
>missing something?
I did leave out one potentially significant factor: diffusional
limitation. If you have a catalyst particle, where much of the
catalyst is in pores in the particle, then the time it takes for the
substrate to get in becomes important. Even with the catalyst or
enzyme on an exposed surface, if the reaction rate is on the order
of or faster than the rate of diffusion, the kinetics also change.
In the case where diffusional resistance is negligable (e.g., the
fluid medium is well mixed, all the catalyst/enzyme is "exposed",
the rate of reaction is much slower than the rate of diffusion) the
kinetics are basically the same.
In fact, many of the cellular enzymes we treat as "in solution" are
contained in membranes, but we can readily treat them with the same
math.
-Paul
