Figure 1.

(A) SPR sensorgrams of Aβ₄₀ binding with a heparin chip. Solutions of Aβ (0.63, 1.25, 2.5, 5, and 10 μM) were flowed over the heparin chip. On the basis of the responses, a K_d value of 15 nM for heparin-Aβ binding was calculated. (B) IC₅₀ values and inhibitory constants of various synthetic HS oligosaccharides binding with Aβ as determined by a solution/surface competition experiments against Aβ binding to heparin immobilized on an SPR sensor. IC₅₀ was calculated based on the protein binding signals from the sensorgrams with the addition of HS oligosaccharides in different concentrations. Solution based affinities (K_i) were calculated from IC₅₀ measured from SPR competition experiments using the equation: K_i = IC₅₀/(1 + [C]/K_D); [C] = protein concentration used in the competition SPR; K_D is protein-heparin binding affinity.