Kinetics of Inhibition of Human Plasma Kallikrein by a Site-Specific Modified Inhibitor Arg’5-Aprotinin: Evaluation Using a Microplate System and Comparison With Other Proteases
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چکیده
Human plasma kallikrein. a product of contact-activated plasma proteolysis. is moderately inhibited by aprotinin. a small polypeptide from bovine lung that has been used as an experimental drug in human disease states. Aprotinin has a Lys residue in the P1 (reactive center) position occupying residue 1 5. Since kallikrein is an argininedirected serine protease. we hypothesized that an altered form of aprotinin. Arg’ -aprotinin. might be a better inhibitor. Kinetic evaluations were performed in 96-well microplates. We found that the KL (loose or Michaelis-Menten complex) was unchanged by the modification. However. the association rate constant was increased from 1 .14 x i04 (mol/L)’s1 to 1.5 x 1O (mol/LY1s’. thus indicating that the inhibition rate was increased 14-fold for the modified protein. The K, (at equilibrium) was decreased from 3.2 x iO-7 mol/L to 1 .5 x iO mol/L after substituting Arg for Lys in the P1 position. Therefore. the modified
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Kinetics of inhibition of human plasma kallikrein by a site-specific modified inhibitor Arg15-aprotinin: evaluation using a microplate system and comparison with other proteases.
Human plasma kallikrein, a product of contact-activated plasma proteolysis, is moderately inhibited by aprotinin, a small polypeptide from bovine lung that has been used as an experimental drug in human disease states. Aprotinin has a Lys residue in the P1 (reactive center) position occupying residue 15. Since kallikrein is an arginine-directed serine protease, we hypothesized that an altered f...
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