Fig. 2: Catalytic amide bond hydrolysis of nitrocefin by the PSMα assemblies.
From: Staphylococcus aureus functional amyloids catalyze degradation of β-lactam antibiotics
A scheme of nitrocefin β-lactam ring opening and degradation (top row). a Graph depicting degradation of nitrocefin (initial nitrocefin concentration 60 µM) in the presence of PSMα assemblies (350 µM). b Initial nitrocefin-degradation reaction rate, V0, as a function of initial preassembled-PSMα concentration (the peptides were pre-incubated in water for two hours and then buffered with Hepes prior to mixing with nitrocefin at concentration of 60 µM). The inset depicts the low-concentration peptide region, underscoring a negligible catalytic activity at V0 lower than 30 μM. The values are represented as average ± SEM, N = 3. c Initial nitrocefin-degradation reaction rate as function of initial nitrocefin concentration (PSMα peptide concentrations of 170 µM). Each point represents an average ± SEM, NPSMα1 = 8, NPSMα2 = 19, NPSMα3 = 10, NPSMα4 = 5. The dotted line is the fitting to a Michaelis-Menten (MM) model using non-linear regression. d The catalytic efficiency (ε) is derived from the fitting to MM model (using the catalytic parameters in Table S1). The values represented as the calculated ratio (Kcat/KM) and the error bars are the confidence interval, derived from the fitting to the model. Source data are provided as a Source Data file.
