Why does the positive regulation in bacteriophage λ affect isomerization of the RNAP-DNA complex?

The initiation of transcription involves three steps: binding, opening, and escape of RNA polymerase. To model these steps in the simplest way we will treat opening and escape as a single reaction with forward reaction rate k determined by the regulatory proteins and their interaction with the DNA. Binding will be treated as a reversible reaction with an equilibrium constant KB. Using mathematical models, it is demonstrated that in the phage λ induction the binding constant KB plays a fundamentally different role from the opening and clearing constant k. In particular modifications in KB cannot be directly compensated for by modifications in k and vice versa.