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The role of axial ligands for the structure and function of chlorophylls

Heimdal, Jimmy LU ; Jensen, Kasper LU ; Devarajan, Ajitha LU and Ryde, Ulf LU (2007) In Journal of Biological Inorganic Chemistry 12(1). p.49-61
Abstract
We have studied the effect of axial ligation of chlorophyll and bacteriochlorophyll using density functional calculations. Eleven different axial ligands have been considered, including models of histidine, aspartate/glutamate, asparagine/glutamine, serine, tyrosine, methionine, water, the protein backbone, and phosphate. The native chlorophylls, as well as their cation and anion radical states and models of the reaction centres P680 and P700, have been studied and we have compared the geometries, binding energies, reduction potentials, and absorption spectra. Our results clearly show that the chlorophylls strongly prefer to be five-coordinate, in accordance with available crystal structures. The axial ligands decrease the reduction... (More)
We have studied the effect of axial ligation of chlorophyll and bacteriochlorophyll using density functional calculations. Eleven different axial ligands have been considered, including models of histidine, aspartate/glutamate, asparagine/glutamine, serine, tyrosine, methionine, water, the protein backbone, and phosphate. The native chlorophylls, as well as their cation and anion radical states and models of the reaction centres P680 and P700, have been studied and we have compared the geometries, binding energies, reduction potentials, and absorption spectra. Our results clearly show that the chlorophylls strongly prefer to be five-coordinate, in accordance with available crystal structures. The axial ligands decrease the reduction potentials, so they cannot explain the high potential of P680. They also redshift the Q band, but not enough to explain the occurrence of red chlorophylls. However, there is some relation between the axial ligands and their location in the various photosynthetic proteins. In particular, the intrinsic reduction potential of the second molecule in the electron transfer path is always lower than that of the third one, a feature that may prevent back-transfer of the electron. (Less)
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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
density functional theory, axial ligands, chlorophyll, photosynthesis, reduction potential
in
Journal of Biological Inorganic Chemistry
volume
12
issue
1
pages
49 - 61
publisher
Springer
external identifiers
  • wos:000242462600005
  • scopus:33845362034
  • pmid:16953415
ISSN
1432-1327
DOI
10.1007/s00775-006-0164-z
language
English
LU publication?
yes
additional info
The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Theoretical Chemistry (S) (011001039)
id
be4a0a6c-e618-4551-ad2d-ff1b24600a87 (old id 685162)
date added to LUP
2016-04-01 12:35:59
date last changed
2020-12-08 02:26:06
@article{be4a0a6c-e618-4551-ad2d-ff1b24600a87,
  abstract     = {We have studied the effect of axial ligation of chlorophyll and bacteriochlorophyll using density functional calculations. Eleven different axial ligands have been considered, including models of histidine, aspartate/glutamate, asparagine/glutamine, serine, tyrosine, methionine, water, the protein backbone, and phosphate. The native chlorophylls, as well as their cation and anion radical states and models of the reaction centres P680 and P700, have been studied and we have compared the geometries, binding energies, reduction potentials, and absorption spectra. Our results clearly show that the chlorophylls strongly prefer to be five-coordinate, in accordance with available crystal structures. The axial ligands decrease the reduction potentials, so they cannot explain the high potential of P680. They also redshift the Q band, but not enough to explain the occurrence of red chlorophylls. However, there is some relation between the axial ligands and their location in the various photosynthetic proteins. In particular, the intrinsic reduction potential of the second molecule in the electron transfer path is always lower than that of the third one, a feature that may prevent back-transfer of the electron.},
  author       = {Heimdal, Jimmy and Jensen, Kasper and Devarajan, Ajitha and Ryde, Ulf},
  issn         = {1432-1327},
  language     = {eng},
  number       = {1},
  pages        = {49--61},
  publisher    = {Springer},
  series       = {Journal of Biological Inorganic Chemistry},
  title        = {The role of axial ligands for the structure and function of chlorophylls},
  url          = {http://dx.doi.org/10.1007/s00775-006-0164-z},
  doi          = {10.1007/s00775-006-0164-z},
  volume       = {12},
  year         = {2007},
}