FIGURE 2.

Process of heparin binding to AT III. The binding of heparin with AT III is a reversible process. This process involves native unactivated (AT III, PDB code 1E05), intermediate-activated (AT III*, PDB code 1NQ9) and fully activated (AT III**, 1E03) states. During the binding process, IdoA transforms from conformational equilibrium to a complete ²S₀ conformation (Jimenez-Barbero and Peters, 2003). The models of the three states are derived from X-ray. The reactive center loop (RCL) (red), sheet A (green), and helix D (gray blue) and the helix extension (dark blue) are highlighted in each state.