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Theoretical study of the electronic spectrum of plastocyanin

Pierloot, Kristine; De Kerpel, Jan O A; Ryde, Ulf LU and Roos, Björn O. LU (1997) In Journal of the American Chemical Society 119(1). p.218-226
Abstract

The electronic spectrum of the blue copper protein plastocyanin has been studied by ab initio multiconfigurational second-order perturbation theory (the CASPT2 method). The six lowest electronic transitions have been calculated and assigned with an error of less than 2000 cm-1. The singly occupied orbital in the ground state is Cu 3d-S(Cys) 3pπ antibonding with some N(His) 2pσ character. The bright blue color originates from an electron transfer to this orbital from the corresponding Cu 3d-S(Cys)3pπ bonding orbital. The influence of different ligand models on the spectrum has been thoroughly studied; Cu(imidazole)2(SCH3)(S(CH3)2)+ as a model of CuHis2CysMet is... (More)

The electronic spectrum of the blue copper protein plastocyanin has been studied by ab initio multiconfigurational second-order perturbation theory (the CASPT2 method). The six lowest electronic transitions have been calculated and assigned with an error of less than 2000 cm-1. The singly occupied orbital in the ground state is Cu 3d-S(Cys) 3pπ antibonding with some N(His) 2pσ character. The bright blue color originates from an electron transfer to this orbital from the corresponding Cu 3d-S(Cys)3pπ bonding orbital. The influence of different ligand models on the spectrum has been thoroughly studied; Cu(imidazole)2(SCH3)(S(CH3)2)+ as a model of CuHis2CysMet is the smallest system that gives converged results.The spectrum is surprisingly sensitive to changes in the geometry, especially in the Cu-S bond distances; a 5 pm change in the Cu-S(Cys) bond length may change the excitation energies by as much as 2000 cm-1. The effect of the surrounding protein and solvent on the transition energies has been modeled by point charges and is found to be significant for some of the transitions (up to 2000 cm-1).

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publishing date
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Contribution to journal
publication status
published
subject
in
Journal of the American Chemical Society
volume
119
issue
1
pages
9 pages
publisher
The American Chemical Society
external identifiers
  • scopus:0031042264
ISSN
0002-7863
DOI
10.1021/ja962381f
language
English
LU publication?
yes
id
e99b8d2b-c945-4795-b40f-d9d1d9971bb2
date added to LUP
2017-02-04 11:34:21
date last changed
2017-06-20 11:00:50
@article{e99b8d2b-c945-4795-b40f-d9d1d9971bb2,
  abstract     = {<p>The electronic spectrum of the blue copper protein plastocyanin has been studied by ab initio multiconfigurational second-order perturbation theory (the CASPT2 method). The six lowest electronic transitions have been calculated and assigned with an error of less than 2000 cm<sup>-1</sup>. The singly occupied orbital in the ground state is Cu 3d-S(Cys) 3pπ antibonding with some N(His) 2pσ character. The bright blue color originates from an electron transfer to this orbital from the corresponding Cu 3d-S(Cys)3pπ bonding orbital. The influence of different ligand models on the spectrum has been thoroughly studied; Cu(imidazole)<sub>2</sub>(SCH<sub>3</sub>)(S(CH<sub>3</sub>)<sub>2</sub>)<sup>+</sup> as a model of CuHis<sub>2</sub>CysMet is the smallest system that gives converged results.The spectrum is surprisingly sensitive to changes in the geometry, especially in the Cu-S bond distances; a 5 pm change in the Cu-S(Cys) bond length may change the excitation energies by as much as 2000 cm<sup>-1</sup>. The effect of the surrounding protein and solvent on the transition energies has been modeled by point charges and is found to be significant for some of the transitions (up to 2000 cm<sup>-1</sup>).</p>},
  author       = {Pierloot, Kristine and De Kerpel, Jan O A and Ryde, Ulf and Roos, Björn O.},
  issn         = {0002-7863},
  language     = {eng},
  month        = {01},
  number       = {1},
  pages        = {218--226},
  publisher    = {The American Chemical Society},
  series       = {Journal of the American Chemical Society},
  title        = {Theoretical study of the electronic spectrum of plastocyanin},
  url          = {http://dx.doi.org/10.1021/ja962381f},
  volume       = {119},
  year         = {1997},
}