Scaling law for the non-exponential ligand rebinding of CO in myoglobin

The non-exponential kinetics of the rebinding in myoglobin is simulated by universal functions such as a Havriliak-Negami function, a rational approximation or a modified stretched exponential all of which depend on time via a scaling variable (t/τ12(T))β(T). For the scaling parameters, the half-decay time τ12 and the exponent β the temperature dependence including tunneling effects are analyzed. It is shown that the scaling properties imply temperature-dependent distributions of activation energies and the existence of a critical temperature T∗ ∼ 170–190 K above which no positive static distribution exists.