Binding sites of pyridine in cytochrome P-450cam.

Careful titration of oxidized cytochrome P-450cam from Pseudomonas putida with pyridine revealed deviations of the Eadie plot from linearity in the substrate-bound as well as in the substrate-free protein. A binding model which assumes two binding sites for pyridine--the iron and the camphor binding site--is able to describe completely the nonlinear Eadie plot.