Fig. 5.
Influence of cofactors on the distribution of PAI-1 over the substrate and inhibition pathway. The apparent stoichiometry for the inhibition of thrombin-VR1 by PAI-1 in the presence of increasing amounts of heparin (A), or vitronectin (B) were determined as described under Experimental Procedures. These titrations were performed at concentrations of thrombin-VR1 of 20 nmol/L (A) or 4 nmol/L (B) with an increasing concentration of PAI-1 (from 0 nmol/L to 50 nmol/L) to determine the apparent stoichiometry. This apparent stoichiometry represents 1 + the partition ratio (k3 /k4 ), as depicted in Fig 2.
