February 21, 2023
International Journal Of Molecular Sciences
Product: SNAPtide® Peptide Substrate (FITC/DABCYL) for C. botulinum Type A Neurotoxin
3. Experimental
3.1. Assays
3.1.1. General
All biochemical analyses and cell assays were performed as previously reported by Lin et al. [22] and Turner, Nielsen et al. [14] with the following modifications.
3.1.2. SNAPtide Enzyme Activity Assay
The assay was conducted as previously described [22]. The final assay concentrations are as follows: SNAPtide substrate #523 = 4 µM; BoNT/A LC = 10 nM; assay buffer = 40 mM HEPES pH 7.4, 0.01% Triton X-100, 1% DMSO.
3.1.3. Screening
Initial compound screening was performed at room temperature with SNAPtide substrate #521 (List Labs, Campbell, CA, USA) at a compound concentration of 40 µM.
3.1.4. Endpoint Assay
In total, 500 nM BoNT/A LC was incubated with 5 µM of each compound for 30 min at 37 °C. At the indicated timepoints, 2 µL aliquots were quenched in 48 µL of SNAPtide #523 substrate (25-fold dilution) to give a SNAPtide assay final concentration of 20 nM BoNT/A LC and 0.2 µM compound.