Structure and vibrational dynamics of model compounds of the [fefe]-hydrogenase enzyme system via ultrafast two-dimensional infrared spectroscopy

Stewart, A.I. and Clark, I.P. and Towrie, M. and Ibrahim, S.K. and Parker, A.W. and Pickett, C.J. and Hunt, Neil T. (2008) Structure and vibrational dynamics of model compounds of the [fefe]-hydrogenase enzyme system via ultrafast two-dimensional infrared spectroscopy. Journal of Physical Chemistry B, 112 (32). pp. 10023-10032. ISSN 1520-6106

Abstract

Ultrafast two-dimensional infrared (2D) spectroscopy has been applied to study the structure and vibrational dynamics of (mu-S(CH2)(3)S)Fe-2(CO)(6), a model compound of the active site of the [FeFe]-hydrogenase enzyme system. Comparison of 2D-IR spectra of (mu-S(CH2)(3)S)Fe-2(CO)(6) with density functional theory calculations has determined that the solution-phase structure of this molecule is similar to that observed in the crystalline phase and in good agreement with gas-phase simulations. In addition, vibrational coupling and rapid (< 5 ps) solvent-mediated equilibration of energy between vibrationally excited states of the carbonyl ligands of the di-iron-based active site model are observed prior to slower (similar to 100 ps) relaxation to the ground state. These dynamics are shown to be solvent-dependent and form a basis for the future determination of the vibrational interactions between active site and protein.

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