title: Kinetics of binding between thermolysin and Streptomyces metalloprotease inhibitor, talopeptin (MKI).
abstract: The mechanism of binding between thermolysin with its specific inhibitor, talopeptin (MKI), was studied kinetically with the stopped-flow method by monitoring the enhancement of tryptophan fluorescence caused by the complex formation. Only one relaxation obeying first-order kinetics was observed. The dependence of the apparent first-order constant, kapp, on the inhibitor concentration is consistent with a minimum two-step mechanism, including a fast bimolecular binding step followed by a slow unimolecular step. It was found that the increase in tryptophan fluorescence occurs solely in the slow unimolecular step. The apparent second-order rate constant, (kon)app, in the low inhibitor concentration range, was determined over the pH range between 5 and 8.5 and decreases with increasing pH. The activation parameters for the overall binding process were obtained from the temperature dependence of (kon)app.
mesh_terms: D006020:Glycopeptides / Q000494:pharmacology*; D007700:Kinetics; D008666:Metalloendopeptidases; D008956:Models, Chemical; D011480:Protease Inhibitors; D011485:Protein Binding; D013050:Spectrometry, Fluorescence; D013302:Streptomyces / Q000378:metabolism; D013696:Temperature; D013820:Thermolysin / Q000037:antagonists & inhibitors*
chemical_list: D006020:Glycopeptides; D011480:Protease Inhibitors; C037819:talopeptin; D008666:Metalloendopeptidases; D013820:Thermolysin