Summary
Rates of hydrolysis of the newly developed peptide chromogenic substrates S-2160 (N-Bz-Phe-Val-Arg-pNA,
HCl), S-2238 (H-D-Phe-Pip-Arg-pNA, 2HC1), S-2222 (N-Bz-Ile-Glu-Gly-Arg-pNA, HC1),
and S-2251 (H-D-Val-Leu-Lys-pNA, 2HC1) from AB Kabi Peptide Research and Chromozym
TH (Z-Gly-Pro-Arg-pNA, HC1) from Pentapharm Limited were tested against highly purified
preparations of human plasmin, bovine trypsin, human alpha thrombin, and bovine factor
Xa.
S-2160, S-2238, and Chromozym TH are sensitive to thrombin, Chromozym TH and S-2238
exhibiting a substantially greater sensitivity than S-2160. All 3 substrates are insensitive
to factor Xa but hydrolyzed to varying degrees by plasmin and trypsin. In contrast,
S-2222 is sensitive to Xa and insensitive to thrombin. S-2251 is relatively plasmin-specific,
being resistant to the clotting enzymes thrombin and Xa. S-2251 exhibits even greater
sensitivity to the SK-plasmin complex than to plasmin. In addition, the substrate
Chromozym PK (N-Bz-Pro-Phe-Arg-pNA, HC1) was evaluated and found to be relatively
specific for plasma kallikrein. Assays for antithrombin III and heparin using S-2222
as the substrate and factor Xa as the enzyme, plasma plasminogen and plasmin inhibitors
using S-2251 as the substrate, and plasma prekallikrein and kallikrein inhibitors
using Chromozym PK as the substrate have been developed. Synthetic peptides mimicking
amino acid sequences adjacent to proteolytic activation cleavage of plasma serine
protease precursors appear to be sensitive and relatively specific tools applicable
to kinetical and clinical studies of these enzymes and their inhibitors.
