The two principal kinetic constants that are useful in describing mechanism-based inactivation are kinact (the maximum rate of inactivation) and Kkinact_half (in literature also often referred to as KI, the concentration at which the inactivation rate is half-maximal). Based on the reaction scheme shown above and with the typical assumption of quasi steady-state, it can be shown that kinact is a complex mixture of k2, k3, and k4, while Kkinact_half is a complex mixture of k1, k-1, k2, k3, and k4: