Cryo-EM analysis furnishes remarkable structural information on the PFK/nitrocefin complexation, complementing the MD simulations, and further illuminating the allosteric catalytic mechanism. The raw micrographs in Figure reveal a significant difference between the morphologies of the PFK fibrils with and without nitrocefin. Specifically, the bare PFK amyloid fibrils (without added nitrocefin) form thin single fibers (Figure , left), while thicker, intertwined fiber assemblies can be discerned following incubation with nitrocefin (Figure , right).