DSC study of glycerol-extracted muscle fibers in intermediate states of ATP hydrolysis |
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Authors: | T Dergez F Könczöl N Farkas J Belőgyi D Lõrinczy |
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Institution: | (1) Instituto de Química - UNESP, Departamento de Físico-Química, CP 355, CEP 14801-970 Araraquara - SP, Brazil;(2) Instituto de Química - UNESP, Departamento de Físico-Química, CP 355, CEP 14801-970 Araraquara - SP, Brazil |
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Abstract: | Summary The heat capacity of contractile proteins actin and myosin was studied in psoas muscle of rabbit in strongly and weakly binding state of myosin to actin as a function of temperature by DSC. Deconvolution of the unfolding scans makes possible to characterize the structural domains of the macromolecules. We tried to approach the unfolding process in different intermediate state of ATP hydrolysis. The thermal transitions were calorimetrically irreversible, therefore the two-state irreversible model that describes fairly well the denaturation of different proteins was used for evaluation of the denaturation processes in muscle fibers in strongly (rigor, ADP) and weakly binding states (ATP·Vi, ADP·AlF4) of myosin to actin. Deconvolution resulted in four transitions, the first three transition temperatures were almost independent of the intermediate states of muscle, the last transition temperature was shifted to higher temperature, when the buffer solution was manipulated. The mean values in strongly binding states were Tm1=52.9±0.7°C, Tm2=57.9±0.7°C, Tm3=63.7±1.0°C and Tm4=67.8±0.7°C, but the last transition increased to higher temperature depending on the Pi analogue. |
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Keywords: | phase transformations thermal behavior Cu-Al alloys Ag addition |
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