Enzymology researchers involved in drug discovery, if and when actually using the "k obs " method, should pay close attention the overall shape of k obs plot. Any such plots that show local minima near [I] 0 ≈ [E] 0 strongly indicate the actual presence of tight-binding in the assay. If so, Eqn (6) rather than the usual classical formulas should be used to interpret the k obs results.