For laboratory use only. S-2366 is a chromogenic substrate for factor XI and activated protein C.The substrate can be used for the determination of purified enzyme preparations as well as of Protein C and FXI in plasma. S-2366 is also readily split by trypsin, thrombin, plasmin and tissue plasminogen activator. It is split by FXIIa, plasma kallikrein and FXa as well.