Fig. 2.

BoNT-B in the presence of Zn²⁺ cleaves Sb2-H6, but not Sx1A-H6, as indicated by Western blot analysis (A and F). (B) Bright-field images of cantilevers that were subjected to indirect immunochemistry in C. Cantilevers incubated with Sx1A-H6 (+) were successfully functionalized as indicated by the positive immunoreactivity compared with the control cantilevers for which Sx1A-H6 was omitted from the incubation solution (-). Treatment of the functionalized cantilevers with Zn²⁺ alone or BoNT-B/Zn²⁺ did not reduce the syntaxin 1A immunoreactivity on cantilevers, consistent with the Western blot analysis in A. (D) Beads functionalized with Sb2-H6 (+) showed positive immunoreactivity compared with control beads for which Sb2-H6 was not attached to the bead (-). Treatment of the functionalized beads with Zn²⁺ alone or BoNT-B/Zn²⁺ indicated that BoNT-B/Zn²⁺ greatly reduced the synaptobrevin 2 reactivity on the bead (compare images in D and E), consistent with Western blot analysis in F. (E) Bright-field images of beads in D. (Scale bar in the right-most image in E indicates 100 μm for all images in B-E.)