Figure. 1.

Evaluation of PAI-1 binding to nickel using surface plasmon resonance. Nickel was bound to an NTA-coupled chip, and PAI-1 binding was measured at equilibrium using SPR by injecting varying concentrations and flowing the solution over the chip (see Materials and Methods). In Panel A, the change in response units upon binding of active (•) or latent (○) PAI-1 to immobilized nickel was corrected for nonspecific binding, normalized, and fit to the equation for a hyperbolic binding function [Eq. (2)] with a single binding site. The dissociation constants for binding are calculated to be 6.5 ± 0.2 μM and 22 ± 3 μM for native and latent PAI-1, respectively. In Panel B, varying concentrations of magnesium chloride were mixed with PAI-1 (2 μM) and then passed over immobilized nickel on the NTA-chip.