Journal article
The importance of vibronic perturbations in ferrocytochrome c spectra: A reevaluation of spectral properties based on low-temperature optical absorption, resonance Raman, and molecular-dynamics simulations
The Journal of chemical physics, v 123(5), pp 054508-054508-12
09 Aug 2005
PMID: 16108670
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Abstract
We have measured and analyzed the low-temperature
(
T
=
10
K
)
absorption spectrum of reduced horse heart and yeast cytochrome c. Both spectra show split and asymmetric
Q
0
and
Q
v
bands. The spectra were first decomposed into the individual split vibronic sidebands assignable to
B
1
g
(
ν
15
)
and
A
2
g
(
ν
19
,
ν
21
, and
ν
22
) Herzberg-Teller active modes due to their strong intensity in resonance Raman spectra acquired with
Q
0
and
Q
v
excitations. The measured band splittings and asymmetries cannot be rationalized solely in terms of electronic perturbations of the heme macrocycle. On the contrary, they clearly point to the importance of considering not only electronic perturbations but vibronic perturbations as well. The former are most likely due to the heterogeneity of the electric field produced by charged side chains in the protein environment, whereas the latter reflect a perturbation potential due to multiple heme-protein interactions, which deform the heme structure in the ground and excited states. Additional information about vibronic perturbations and the associated ground-state deformations are inferred from the depolarization ratios of resonance Raman bands. The results of our analysis indicate that the heme group in yeast cytochrome c is more nonplanar and more distorted along a
B
2
g
coordinate than in horse heart cytochrome c. This conclusion is supported by normal structural decomposition calculations performed on the heme extracted from molecular-dynamic simulations of the two investigated proteins. Interestingly, the latter are somewhat different from the respective deformations obtained from the x-ray structures.
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Details
- Title
- The importance of vibronic perturbations in ferrocytochrome c spectra: A reevaluation of spectral properties based on low-temperature optical absorption, resonance Raman, and molecular-dynamics simulations
- Creators
- Matteo Levantino - National Institute for the Physics of Matter (INFM) and Department of Physical and Astronomical Sciences, University of Palermo, Via Archirafi 36, 90123 Palermo, ItalyQing Huang - Department of Chemistry, Drexel University, Chestnut Street 3141, Philadelphia, Pennsylvania 19104Antonio Cupane - National Institute for the Physics of Matter (INFM) and Department of Physical and Astronomical Sciences, University of Palermo, Via Archirafi 36, 90123 Palermo, ItalyMonique Laberge - Institute of Biophysics and Radiation Biology, Semmelweis University, Puskin u.9, Budapest,H-1088, Hungary and Department of Biochemistry and Biophysics and Johnson Research Foundation,University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104-6059Andrew Hagarman - Department of Chemistry, Drexel University, Chestnut Street 3141, Philadelphia, Pennsylvania 19104Reinhard Schweitzer-Stenner - Department of Chemistry, Drexel University, Chestnut Street 3141, Philadelphia, Pennsylvania 19104
- Publication Details
- The Journal of chemical physics, v 123(5), pp 054508-054508-12
- Publisher
- American Institute of Physics
- Grant note
- MCB-0318749 / NSF 37406-AC / UNSPECIFIED
- Resource Type
- Journal article
- Academic Unit
- Chemistry
- Web of Science ID
- WOS:000231168700054
- Scopus ID
- 2-s2.0-23944513634
- Other Identifier
- 991014878137804721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Chemistry, Physical
- Physics, Atomic, Molecular & Chemical