| Attributs | Valeurs |
|---|
| type
| |
| Is Part Of
| |
| Subject
| |
| Title
| - Solvent Effects on Conformational Dynamics of Zn-Substituted MyoglobinObserved by Time-Resolved Hole-Burning Spectroscopy
|
| has manifestation of work
| |
| related by
| |
| Author
| |
| Abstract
| - Equilibrium conformational fluctuation of Zn-substituted myoglobin (ZnMb) has been studiedin the nanosecond to millisecond time region and 180−300 K temperature region by the time-resolvedtransient hole-burning spectroscopy. In this technique, the conformational fluctuation of the protein isobserved as the temporal variation of the hole spectrum burned by irradiation of the laser pulse. ZnMbsolution samples in various solvent conditions were prepared and investigated to elucidate the solventeffect on the conformational dynamics of Mb. The configuration coordinate model assuming the harmonicenergy landscape has given a fairly good description of the time dependence of the hole spectra. Theobserved temporal behavior of both the hole shift and the hole broadening was well expressed by thesame stretched exponential correlation function with a rather small and almost temperature-independentβ of 0.26. It was found that the correlation time τc of the conformational fluctuation of ZnMb determinedby this analysis depends linearly on the solvent viscosity regardless of the solvent composition andtemperature. This means the almost 0 activation energy for the fluctuation process and can not be understoodby simply assuming the Arrhenius-type crossing of the barriers separating the conformational substates.It is shown that this linear viscosity dependence of τc, as well as the temperature-independent β, isqualitatively explained in the framework of the hierarchically constrained dynamics (HCD) model [Palmer,R. G. et al. (1984) Phys. Rev. Lett. 53, 958−961] with the postulate that the dynamics in the lowest levelin the HCD model corresponds in the actual system to the configuration fluctuations of the solvent moleculessurrounding the protein.
|
| article type
| |
| is part of this journal
| |
