Journal article
Non‐planar heme deformations and excited state displacements in horseradish peroxidase detected by Raman spectroscopy at Soret excitation
Journal of Raman spectroscopy, v 36(4), pp 363-375
Apr 2005
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Abstract
We studied the out‐of‐plane modes of horseradish peroxidase (HRP) in different spin, oxidation and ligation states by measuring the respective resonance Raman spectra with (near) Soret excitation. The non‐planar modes of the heme are Raman inactive for planar macrocycles, but become resonance Raman active in the presence of out‐of‐plane deformations. The thus induced Raman scattering results mostly from Franck–Condon type coupling. We observed bands from a variety of out‐of‐plane modes such as γ5, γ6, γ7(A2u) modes, γ21 and γ22(Eg), γ15(B2u) and γ11(B1u). The appearance of these bands is clearly indicative of non‐planar deformations of the same symmetry. We determined the relative intensities of all sufficiently intense Raman modes of ferric pentacoordinated, quantum mixed and hexacoordinated low‐spin as well as of ferrous pentacoordinated high‐spin HRP C. The apparent vibronic coupling parameters were obtained from a self‐consistent analysis of the Raman intensities and the respective optical absorption spectrum. They revealed significantly reduced displacements of the excited B‐state for the ferrous, deoxy‐like state compared with the resting ferric state. An analysis of the obtained coupling strengths of out‐of‐plane modes revealed that they are predominantly induced by static non‐planar deformations along the normal coordinates of the lowest wavenumber modes of a given symmetry type. We used the deformations of the heme in resting HRP C to determine the vibronic coupling strength of the experimentally detectable out‐of‐plane modes and subsequently employed this information to obtain the non‐planar deformations for the investigated ferric hexacoordinated low‐spin state. This yielded a substantial reduction of the ruffling distortion, whereas the doming deformation remained mostly unaffected by the change of the iron's spin and ligation state. Copyright © 2005 John Wiley & Sons, Ltd.
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Details
- Title
- Non‐planar heme deformations and excited state displacements in horseradish peroxidase detected by Raman spectroscopy at Soret excitation
- Creators
- Qing HuangReinhard Schweitzer‐Stenner
- Publication Details
- Journal of Raman spectroscopy, v 36(4), pp 363-375
- Publisher
- John Wiley & Sons, Ltd; Chichester, UK
- Number of pages
- 13
- Grant note
- ACS‐Petroleum Research Fund (PRF 37406‐AC.) National Science Foundation (MCB‐0318749.) NIH (P20 RR16439‐01.)
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Chemistry
- Web of Science ID
- WOS:000228912000011
- Scopus ID
- 2-s2.0-18444392102
- Other Identifier
- 991014877924804721
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- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Spectroscopy