Figure 4.

Association and dissociation kinetics for binding of two representative monomeric Affibody constructs to immobilized Aβ₄₂cc protofibrils. Affibody concentrations are 10 (green), 20 (yellow) and 40 nM (red). The data was fitted to a heterogeneous ligand binding model with local maximum response (R_max) values. The kinetics of the slow association and dissociation phases are k _a = 2.8 (±0.1) × 10⁵ s⁻¹ M⁻¹ and k _a = 2.5 (±0.1) × 10⁵ s⁻¹ M⁻¹ and k _d = 4.7 (±0.05) × 10⁻⁴ s⁻¹ and k _d = 6.2 (±0.05) × 10⁻⁴ s⁻¹ for Z_{Aβ42cc_1} (a) and Z_{Aβ42cc_4} (b), respectively, which correspond to dissociation constants for the stronger binding site of K _D = 1.6 (±0.1) and K _D = 2.5 (±0.2) nM, respectively.