Effect of DHG on the kinetics of factor X activation by the intrinsic tenase complex. The kinetics of factor X activation by the intrinsic tenase complex in the presence of 0 nM (•), 1 nM (○), or 2 nM (▪) DHG was determined in reactions containing 1.0 nM factor VIIIa, 0.1 nM factor IXa, 15 to 125 nM factor X, and 50 μM PC/PS in 0.15 M NaCl, 20 mM HEPES (pH 7.4), 2 mM CaCl₂, 1 mg/mL BSA, and 0.1% PEG-8000. Mean values were plotted with error bars representing ± SD (n = 3 to 4). The Km(app) and V_max(app) for factor X activation were determined by fitting the data by nonlinear regression to the Michaelis-Menten equation. The K_max(app) and V_max(app) values ± SE for factor X activation were 25.1 ± 1.7 nM and 7.6 ± 0.2 nM/min, 32.4 ± 1.6 nM and 4.5 ± 0.1 nM/min, and 17.2 ± 1.4 nM and 1.2 ± 0.03 nM/min in the presence of 0, 1, or 2 nM DHG, respectively.