Anticoagulant activity of APC single-point mutants relative to wild-type APC in normal human plasma versus homozygous Q506-FV plasma.

(A) Normal human plasma. (B) Q506-FV plasma. APTT assays were done using plasma mixtures containing 10% normal plasma or 10% Q506-FV plasma and 90% FV-deficient plasma. The percentage of wild-type activity for each APC mutant was calculated as follows. The wild-type APC dose-response data were fit to a line and then that equation was used to calculate a relative amount of wild-type APC for the respective clotting time values for each mutant. For each experiment, values from 2 to 3 concentration points for each mutant were averaged together to get a percent of wild-type APC activity for that experiment. The results of 2 to 3 experiments were averaged together and the SDs are shown as error bars.