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. 2008 Aug 20;3(8):e3023. doi: 10.1371/journal.pone.0003023

Figure 1. Kinetic exclusion analysis (KinExA) of the solution binding properties of the 4LCA antibody and BoNT/A LC.

Figure 1

(A) The equilibrium binding affinity was determined by titrating recombinant BoNT/A LC into solutions of fixed 4LCA concentration. At equilibrium, free 4LCA was captured by passage through a bead matrix conjugated to LC and measured by binding of a fluorescent secondary antibody. The data were fit using the manufacturer's software to a bimolecular binding model, giving an optimized KD value of 31±5×10−12 M. (B) The association rate constant (kon) was measured by mixing 4LCA (200 pM) with LC (10 pM) and measuring the concentration of free antibody concentration over time. The average kon value for 4LCA was estimated to be 2.3±0.1×106 M−1 s−1, which gives a calculated koff value of 7.1×10−5 s−1.