Email: petr.kuzmic@gmail.com (Petr This report describes a data-analytic method that can be used to determine, under tight-binding experimental conditions, not only the association and dissociation rate constants for an reversible enzyme inhibitor but -in certain favorable casessimultaneously also the active enzyme concentration from relevant k obs data. Importantly, it is clarified here that the classical formulas for the dependence of k obs on the total inhibitor concentration cannot and should not be used to determine the number steps appearing in the inhibition mechanism under tightbinding experimental conditions. Nor can those formulas be used, specifically under tight-binding conditions, to determine the dissociation equilibrium constant of a transient enzymeinhibitor complex even if such a complex is in fact present.