A cyclopeptidic suicide substrate preferentially inactivates urokinase-type plasminogen activator.
c[Arg-aB-(CH2+SCH3 phi)-Gly4] was designed and studied as a mechanism-based inactivator (suicide substrate) for plasminogen activators (u-PA and t-PA) and plasmin. This compound inhibited u-PA and fulfills criteria expected for the involvement of an enzyme-activated inhibitor: first-order and irreversible process, saturation kinetics, protection by substrate. The limiting first-order rate constant kinact and the apparent enzyme-inhibitor dissociation constant KI were 0.021 s-1 and 9 microM, respectively at pH 7.5 and 25 degrees C. The activation of plasminogen by u-PA is compromised after this enzyme has been treated by the reagent. Plasmin and t-PA were inactivated 40- and 2330-fold less efficiently than u-PA, respectively.
Reboud-Ravaux
M
M
Laboratoire d'Enzymologie Moléculaire et Fonctionnelle, Institut Jacques Monod, Université de Paris, France.
Vilain
A C
AC
Boggetto
N
N
Maillard
J
J
Favreau
C
C
Xie
J
J
Mazaleyrat
J P
JP
Wakselman
M
M
D000595:Amino Acid Sequence; D001665:Binding Sites; D004792:Enzyme Precursors / Q000037:antagonists & inhibitors; D005341:Fibrinolysin / Q000037:antagonists & inhibitors; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000494:pharmacology*; D010960:Plasminogen Activators / Q000037:antagonists & inhibitors* / Q000652:urine; D015849:Plasminogen Inactivators; D010959:Tissue Plasminogen Activator / Q000037:antagonists & inhibitors; D014568:Urokinase-Type Plasminogen Activator / Q000037:antagonists & inhibitors* / Q000652:urine
D004792:Enzyme Precursors; D010456:Peptides, Cyclic; D015849:Plasminogen Inactivators; D010960:Plasminogen Activators; D010959:Tissue Plasminogen Activator; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator