Circular dichroism for nm (close to the MbCO peak) and nm (close to the Mb peak) as a function of the pump-probe delay. The CD curves are fitted by two exponential functions (7 and 43 psec). The inset shows the corresponding normalized transmission curves.
(a) Sketch of the main aminoacids involved in the CD signal. The residues yielding a positive (resp. negative) rotational strength are drawn in blue (resp. red). The proximal histidine (His93) is singled out due to its particular role: it induces the lifting of the degeneracy of the heme transitions but contributes very little to the rotational strength. His36, His97, Phe46, and Trp7 which are considered in the calculation are not represented because of their weak contribution to the rotational strength. (b) Sketch of the residues with their coordinate axes.
Absorption spectra for (a) MbCO and (b) Mb; CD spectra for (c) MbCO and (d) Mb. The red solid lines are experimental spectra and the black dashed lines are calculated ones.
Calculated spectra for MbCO and Mb and for two intermediate configurations (see text).
Sketch of the electronic levels for the heme and His93 and the normal modes resulting from their coupling. The two low-lying normal modes have rotational strengths of opposite signs.
Calculated CD spectra for a mixing of 80% MbCO and 20% for an isotropic distribution (blue dashed line) and a pump-induced anisotropy (red solid line).
Histogram of the calculated variation of the contribution of the residues to the rotational strength of the high-energy band when passing from (red) and from (blue). See text for the definition of the intermediate structures.
Energy, oscillator strength, and polarization of the electronic transitions of the aromatic pending groups. The polarization is expressed as the angle (in degrees) between the transition moment and the axis (see Fig. 2).
Calculation of the contributions of the transitions of individual residues to the rotational strength of the heme in the Soret band for MbCO and Mb.
Calculation of the contributions of the transitions of individual residues to the rotational strength (in DBM) of the heme in the high-energy band of Mb, , and (see text).
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