Blood coagulation disorders are responsible for the majority of deaths every year in the United States, and better understanding of the pathological causes of coagulation may help prevent these deaths. We utilized high throughput kinetic screening to experimentally bound the plasma concentrations of coagulation proteins that were not feasible to determine with other methods. These proteins were bounded to "engine running" concentrations of tissue factor ( ∼ 40 fM), Factor (F)XIa ( ∼ 5 pM), FXa ( ∼ 10 pM), FIXa ( ∼ 10 pM), FVIIa ( ∼ 1 nM), FVa ( ∼ 300 pM), and thrombin ( ∼ 100 pM). Also, blood was found to be a remarkably robust system that will only double in initiation time ( T i ) when diluted from 2x to 100x. Understanding of coagulation would be incomplete without platelets and neutrophils. The platelet activity when stimulated by ADP, convulxin (CVX), and thrombin receptor agonist peptide (TRAP) was quantified as well. In addition to these experiments, stochastic simulations were performed that found that neutrophils form an average of ∼ 1.5 bonds when tethers are formed between the neutrophil and a P-selectin coated bead. An additional set of simulations found that blood has a 50% chance of reaching an initiating concentration of thrombin within 1 hour when initiated by 186 fM tissue factor. These results provide a consistent framework for the assumption that there is a non-zero "engine running" concentration of activated proteins circulating in plasma.
