We measured the effect of an anti β-lactamase antibody upon PFK fibril-induced nitrocefin hydrolysis (Figure ). This experiment was designed to assess whether the PFK amyloid fibrilinduced β-lactam hydrolysis resembles enzymatic (lactamase) pathways. To prevent salt effects which might modulate antibody structure or interactions with the peptide, PFK fibrils were prepared without KCl at a concentration above the fibrillation threshold [i.e., prepared at a concentration of 5 mM, which is above the critical aggregation concentration (CAC) of PFK ], and subsequently placed in the reaction mixture. Indeed, the visible absorbance curves in Figure demonstrate that the anti-β-lactamase antibody effectively inhibited the catalytic activity of the PFK amyloid fibrils.