A jump in an Arrhenius plot can be the consequence of a phase transition. The binding of ATP to myosin subfragment 1 |
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Authors: | J A Biosca F Travers T E Barman |
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Institution: | INSERM U 128, B.P. 5051, 34033 Montpellier Cedex, France |
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Abstract: | The temperature dependence of the kinetics of the binding of ATP to myosin subfragment-1 was studied by an ATP chase technique in a rapid-flow-quench apparatus: (formula; see text) A temperature range of 30 degrees C to -15 degrees C was obtained with ethylene glycol as antifreeze. The Arrhenius plot of k2 is discontinuous with a jump at 12 degrees C. Above the jump delta H+ = 9.5 kcal/mol, below delta H+ = 28.5 kcal/mol. Few such Arrhenius plots are recorded in the literature but they are predicted from theory. Thus, we explain our results as a phase change of the subfragment 1-ATP system at 12 degrees C. This is in agreement with certain structural studies. |
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Keywords: | Phase transition Myosin subfragment 1 ATP binding to Conformational change |
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