Figure 2. Binding kinetics of fluorescence labeled rCARDS toxin.

(A) rCARDS toxin binding to HeLa cells is concentration dependent. HeLa cells were treated with different concentrations (0.1 to 25 µg/well) of DyLight 649 fluorescence labeled rCARDS toxin for 1 h at 4°C. Cell monolayers were thoroughly washed with cold PBS buffer, and toxin binding was measured using fluorometer. (B) rCARDS toxin binding to HeLa cells is time dependent. HeLa cells were treated with 10 µg of DyLight 649 fluorescence-labeled rCARDS toxin for 15 min to 8 h at 4°C, and binding was analyzed as described above.