Electrochemical activity determination of trypsin-like enzymes. IV. Coupled electrochemical and spectrophotometric assay of thrombin using the same H-D-Phe-Pip-Arg-4 MeO β naphtylamide, 2HCl (S-2421) substrate

The electrochemical activity determination of thrombin has been extended by the use of the carbon paste electrode coupled with the end-point titration procedure. The reliability of this technique is fairly well supported by the availability of the substrate S-2421 : H-D-Phe-Pip-Arg- 4 MeO β naphtylamide, 2HCl: the release of free amine can be monitored either spectrophotometrically or electrochemically. Results show that the kinetic constants of S-2421 obtained using each procedure compare with good agreement. A comparison of the data with those of other chromogenic and electrogenic substrates is given.