PaclitaxelIs an Inhibitor and Its Boron DipyrrometheneDerivative Is a Fluorescent Recognition Agent for Botulinum Neurotoxin Subtype A.

Wehave successfully identified one new inhibitor and one new fluorescentrecognition agent for the botulinum neurotoxin subtype A (BoNT/A)using the virtual screening protocol “protein scanning withvirtual ligand screening” (PSVLS). Hit selection used an in-housedeveloped holistic binding scoring method. Selected hits were testedexperimentally for inhibitory activity using fluorescence resonanceenergy transfer (FRET) assays against the light chain (catalytic domain)of BoNT/A. Ligand binding was determined against the light and heavychain BoNT/A complex through either radiolabeled ligand binding assays(nonfluorescent ligands) or fluorescence intensity assays (fluorescentligands). These experimental assays have confirmed one compound (paclitaxel)to inhibit BoNT/A’s proteolytic activity experimentally withan IC50of 5.2 μM. A fluorescent derivative was alsoconfirmed to bind to the toxin and therefore is a suitable candidatefor the rational design of new detection agents and for the developmentof fluorescence-based multiprobe detection assays. [ABSTRACT FROM AUTHOR]