Fig. 3. Proposed two-state model for the allosteric behavior of RMPK.

E, S, P and I are enzyme, substrate (phosphoenolpyruvate, PEP or ADP), product (pyruvate) and inhibitor (Phe), respectively. E^R and E^T are the two structural states. The species are interconnected with equilibrium constant, L=[E^T]/[E^R]; K^R and K^T are the ligand binding equilibrium constants associated to the E^R- and E^T-state, respectively, while K_I and K_S are the equilibrium constants associated with the binding of inhibitor Phe and substrate, respectively. k^T and k^R are the catalytic rates of E^R and E^T, respectively [16].