Stark-Effect Experiments on Photochemical Holes in Chromoprotiens: Protoporphyrin IX-Substituted Myoglobin

We performed comparative Stark-effect experiments on spectral holes in a protein and a glass sample. The protein was protoporphyrin IX-substituted myoglobin in a glycerol/water solvent. The glass sample was a protoporphyrin IX-doped mixture of dimethylformamide/glycerol. As expected, in both cases t...he spectral holes varied linearly with the electric field. Yet, whereas in the protein the holes showed a clear splitting, they showed no splitting in the glass sample, irrespective of the chosen polarization of the laser. In both samples the hole broadened in the applied field. The magnitude of the broadening was about the same in both cases. The following conclusions were drawn. The absence of a splitting in the glass signals an effective global inversion symmetry of the chromophore, despite its low symmetry group. The dipole moment changes are random. In the protein the inversion symmetry is broken through the spatial correlation of the protein building blocks, leading to a molecular frame-fixed dipole moment difference and, hence, to the observed splitting. Despite these symmetry-breaking properties, the local structural randomness is of the same magnitude in the glass and in the protein, as is obvious from the broadening. The distinct difference in the Stark pattern shows that the Ausführliche Beschreibung Beschreibung ausblenden

1. Person:	Gafert, J.
Weitere Personen:	Friedrich, J. verfasserin; Parak, F. verfasserin
Quelle:	in Proceedings of the National Academy of Sciences of the United States of America Vol. 92, No. 6 (1995), p. 2116-2120 Weitere Artikel
Format:	Online-Artikel
Sprache:	English
Veröffentlicht:	1995
Beschreibung:	Online-Ressource
Schlagworte:	research-article Biophysics Chromophore-Protein Interaction Order-Disorder Phenomena Spectral-Structural Correlations
Online Zugang:	Volltext
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Anmerkung:	Copyright: Copyright 1995 The National Academy of Sciences of the United States of America