Interestingly, if one considers only the lower nitrocefin concentration datapoints (i.e., nitrocefin concentrations < 300 µM, Figure ), the experimental data can be fitted to a Michaelis-Mentenlike catalytic model (Hill coefficient 1.2, parameter table in Figure ). The catalytic parameters extracted from the V0 curves in Figure shed light on the two nitrocefin hydrolysis pathway models. While the binding constants (Kh) are at the same order of magnitude, Kh calculated in the case of the allosteric (sigmoidal) model is lower, indicating stronger binding of the nitrocefin substrate molecule to the PFK amyloid fibrils. Furthermore, the maximal reaction rates, Vmax, yield a significantly higher turnover constant (Kcat) for the allosteric behavior, accounting for faster release of the hydrolyzed nitrocefin reaction product. Overall, the catalytic efficiency (Kcat/Kh) according to the allosteric catalytic model is approximately four times more pronounced than the MM-like model (manifested in low nitrocefin concentrations), indicating that the structural rearrangement of the nitrocefin substrate/PFK fibril complex in higher nitrocefin concentrations significantly enhanced the catalytic efficiency.