I am looking for a chromogenic assay to measure TFPI activity. What substrates will work?

TFPI is a direct inhibitor of FXa, and the TFPI/FXa complex inhibits TF/FVIIa. The chromogenic assay for TFPI is based on the ability of TFPI to inhibit TF/FVIIa catalytic activity in a reaction mixture that contains diluted plasma and known amounts of TF, FVIIa, and FXa. Contact DiaPharma for a detailed protocol.