A fluorescence stopped-flow study on troponin labeled with N-ethyl maleimide and N-(p-(2-benzimidazolyl)phenyl) maleimide.
The kinetics of the conformational change of the troponin-C (TN-C) subunit in N-(p-(2-benzimidazolyl)phenyl) maleimide (BIPM)-N-ethyl maleimide (NEM)-labeled troponin induced by calcium binding or removal were studied with the fluorescence stopped-flow method. The kinetic process of the conformational change was biphasic, the rate constants of the two phases were determined as a function of the free calcium ion concentration of the protein solution. The kinetic behaviour of the conformational change of TN-C in BIPM-NEM-labeled troponin was explained by a simple molecular kinetic mechanism: (Formula: see text) This molecular kinetic mechanism is different from that of the isolated TN-C which we found in the previous work (1). That is, formation of a complex of TN-C with troponin-I (TN-I) and troponin-T (TN-T) modifies the molecular kinetic mechanism of the conformational change of TN-C.
D000818:Animals; D001562:Benzimidazoles; D001665:Binding Sites; D002118:Calcium; D005033:Ethylmaleimide; D007700:Kinetics; D046911:Macromolecular Substances; D008301:Maleimides; D009124:Muscle Proteins; D009132:Muscles / Q000032:analysis; D011485:Protein Binding; D011487:Protein Conformation; D011817:Rabbits; D013050:Spectrometry, Fluorescence; D014336:Troponin
D001562:Benzimidazoles; D046911:Macromolecular Substances; D008301:Maleimides; D009124:Muscle Proteins; D014336:Troponin; D005033:Ethylmaleimide; D002118:Calcium