Kinetics of conformational change of troponin-C induced by proton binding or removal in the absence of calcium ions.
The kinetics of the conformational change of troponin-C induced by binding or removal of protons was studied by a stopped-flow pH-jump spectrofluorometric method. In the pH-down experiment (to investigate the kinetics of conformational change from the deprotonated state to the protonated state), a single first-order reaction with a rate constant and amplitude of 1.75-2.4 sec-1 and around 10% respectively, was observed. On the other hand, two first-order reactions with rate constants of 0.84-1.6 sec-1 and 0.08-0.4 sec-1 were observed in the pH-up experiment, the total amplitudes of these reactions being around 10-20%. The pH dependences of the rate constants of these reactions were analyzed in terms of a three-species mechanism.
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008956:Models, Chemical; D009124:Muscle Proteins; D011487:Protein Conformation; D011817:Rabbits; D014336:Troponin
D009124:Muscle Proteins; D014336:Troponin; D008274:Magnesium; D002118:Calcium