Related Experiment Video
Updated: Aug 19, 2026

Affinity Purification of a Fibrinolytic Enzyme from Sipunculus nudus
Published on: June 2, 2023
Dual effect of synthetic plasmin substrates on plasminogen activation
K Kolev1, W G Owen, R Machovich
1Department of Biochemistry II, Semmelweis University of Medicine, Budapest, Hungary.
Abstract:
The effect of plasmin substrates D-valyl-L-leucyl-lysine-p-nitroanilide (S-2251) and H-D-norleucyl-hexahydrotyrosyl-lysine-p-nitro-anilide (Spectrozyme-PL) on the rate of activation of native human plasminogen in physiological salt solution is studied. Plasminogen activation by two-chain urokinase-type plasminogen activator (urokinase), two-chain tissue-type plasminogen activator (tc-tPA) or trypsin, but not by single chain tPA (sc-tPA) is increased 5- to 10-fold by both substrates, as determined by electrophoretic and spectrophotometric kinetic analysis. The amidolytic activity of sc-tPA, on the other hand, is inhibited by the plasmin substrates in a non-competitive manner (K1 of 6.4 . 10(-4) M for S-2251 and 2.9 . 10(-4) M for Spectrozyme-PL), whereas urokinase and tc-tPA activities are not affected. It is concluded that plasmin substrates containing a lysine residue have a general capacity to enhance plasminogen activation presumably by inducing a conformational change in the native zymogen in a manner similar to 6-aminohexanoate, while the same substrates are inhibitory both on the amidolytic activity of sc-tPA and the activation of native and des1-77-plasminogen by sc-tPA.
More Related Videos
Related Concept Videos
Enzyme Inhibition
Direct-Acting Cholinergic Agonists: Pharmacokinetics
Indirect-Acting Cholinergic Agonists: Chemistry and Structure-Activity Relationship
Reversible inhibitors display short to medium durations of action. Short-acting agents include simple alcohols with...
Indirect-Acting Cholinergic Agonists: Mechanism of Action
Reversible inhibitors like edrophonium bind to a specific part of the enzyme called the anionic catalytic site. They form noncovalent bonds, which means they are not strongly attached to the enzyme. This creates a temporary and less stable enzyme–inhibitor complex, leading to...
Anticoagulant Drugs: Low-Molecular-Weight Heparins
Clot Retraction and Fibrinolysis

