Thermal transitions of actin |
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Authors: | D L?rinczy Zsuzsanna Vértes Franciska Könczöl J Belágyi |
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Institution: | (1) Institute of Biophysics, University Pécs, Faculty of Medicine, Szigeti u. 12, 7624 Pécs, Hungary;(2) Institute of Physiology, University Pécs, Faculty of Medicine, Szigeti u. 12, 7624 Pécs, Hungary;(3) Institute of Forensic Medicine, University Pécs, Faculty of Medicine, Szigeti u. 12, 7624 Pécs, Hungary |
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Abstract: | Actin is one of the main components in the eukaryote cells which plays significant role in many cellular processes, like force-generation,
maintenance of the shape of cells, cell-division cycle and transport processes.
In this study the thermal transitions of monomer and polymerized actins were studied to get information about the changes
induced by polymerization and binding of myosin to actin using DSC and EPR techniques. The main thermal transition of F-actin
was at 67.5°C by EPR using spin-labeled actin (the relative viscosity change was around 62°C), while the DSC denaturation
T
ms were at 60.3d°C for G-actin and at 70.5°C for F-actin.
Applying the Lumry-Eyring model to obtain the parameters of the kinetic process and calculate the activation energy, a ‘break’
was found for F-actin in the function of first-order kinetic constant vs. 1/T. This indicates that an altered interdomain interaction is present in F-actin. The addition of myosin or heavy meromyosin
(HMM) in different molar ratio of myosin to actin has changed significantly the EPR spectrum of spin-labeled F-actin, indicating
the presence of the supramolecular complex. Analyzing the DSC traces of the actomyosin complex it was possible to identify
the different structural domains of myosin and actin. |
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Keywords: | DSC EPR F-actin G-actin myosin thermal unfolding |
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