Binding of EGF1 domain peptide in coagulation factor VII with tissue factor and its implications for the triggering of coagulation.

The binding function of EGF1 domain peptide with tissue factor (TF) and its ability of triggering coagulation were explored. The TF expression model in vitro was established by lipopolysaccharide induction. The affinity of EGFP-EGF1 and TF expressing cells was analyzed by fluorescence microscopy and flow cytometry (FCM). The affinity of EGFP-EGF1 and rat soluble TF was quantitated by surface plasmon resonance (SPR). The ability of EGFP-EGF1 in triggering coagulation was tested by prothrombin time assay. The FCM results showed recombinant factor VII (rFVII) could definitely depress the integration of EGFP-EGF1 with recombinant TF (rTF) (68.65%+/-3.86% vs 57.98%+/-4.71%, P<0.01). The SPR results indicated the association constant ka of EGFP-EGF1 proteins was higher than rFVII (8.29+/-1.39 vs 3.75+/-0.32, P<0.01). However, the EGFP-EGF1 protein lost the activity of triggering coagulation as compared with blood plasma of normal SD rats (56.8+/-3.2 s vs 17.8+/-3.4 s, P<0.01). It was concluded that the rat EGF1 peptide could specifically bind to TF without the ability of triggering coagulation. EGF1 peptide may be a good target head for delivering drugs to TF in anticoagulation therapy.