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. Author manuscript; available in PMC: 2012 Dec 7.
Published in final edited form as: Structure. 2011 Dec 7;19(12):1744–1751. doi: 10.1016/j.str.2011.10.015

Figure 3.

Figure 3

Proposed association mechanisms of three complexes. (a) Hirudin/thrombin association. First the acidic C-terminal tail (in green) of hirudin docks to the fibrinogen recognition site on thrombin (gray surface); then the N-terminal domain (in red) coalesces around the active site. (b) Streptokinase/plasmin association. First the β domain (in green) of streptokinase docks to plasmin (cyan surface); subsequently the α and γ domains (in red and blue, respectively) coalesce around plasmin to form a tight complex. (c) Ribonuclease inhibitor/ribonuclease A association. Ribonuclease inhibitor (in cyan) undergoes conformational fluctuations, resulting in variations in the horseshoe opening. Small opening prevents the binding of ribonuclease A (in green); large opening allows deep insertion of the enzyme, and subsequently contraction leads to a tight complex.