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Importance of proximal hydrogen bonds in haem proteins.

Jensen, Kasper LU and Ryde, Ulf LU (2003) In Molecular Physics 101(13). p.2003-2018
Abstract
We have used the density functional B3LYP method to study the effect of hydrogen bonds from the histidine ligand in various haem proteins to carboxyl groups or to the carbonyl backbone. Hydrogen bonds to carbonyl groups (encountered in globins and cytochromes, for example) have a small influence on the geometry and properties of the haem site. However, hydrogen bonds to a carboxyl group (encountered in peroxidases and haem oxidase) may have a profound effect. The results indicate that in the Fe3+ state, this leads to a deprotonation of the histidine ligand, whereas in the Fe2+ state, the proton involved in the hydrogen bond may reside on either histidine or the carboxylate group, depending on the detailed structure of the surroundings. If... (More)
We have used the density functional B3LYP method to study the effect of hydrogen bonds from the histidine ligand in various haem proteins to carboxyl groups or to the carbonyl backbone. Hydrogen bonds to carbonyl groups (encountered in globins and cytochromes, for example) have a small influence on the geometry and properties of the haem site. However, hydrogen bonds to a carboxyl group (encountered in peroxidases and haem oxidase) may have a profound effect. The results indicate that in the Fe3+ state, this leads to a deprotonation of the histidine ligand, whereas in the Fe2+ state, the proton involved in the hydrogen bond may reside on either histidine or the carboxylate group, depending on the detailed structure of the surroundings. If the histidine is deprotonated, the axial Fe-N bond length decreases by 0.15 Å, whereas the equatorial bond lengths increase. Moreover, the charge on iron and histidine is reduced, as is the spin density on iron. Most importantly, the energy difference between the high and intermediate spin states changes so that whereas the two spin states are degenerate in the Fe2+ state for the protonated histidine, they are degenerate for the Fe3+ state when it is deprotonated. This may facilitate the spin-forbidden binding of dioxygen and peroxide substrates, which takes place for the Fe2+ state in globins but in the Fe3+ state in peroxidases. The reduction potential of the haem group decreases when it hydrogen-bonds to a negatively charged group. The inner-sphere reorganization energy of the Fe2+/Fe3+ transition in a five-coordinate haem complex is ˜30 kJ mol−1, except when the histidine ligand is deprotonated without any hydrogen-bond interaction. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Molecular Physics
volume
101
issue
13
pages
2003 - 2018
publisher
Taylor & Francis
external identifiers
  • wos:000184449300008
  • scopus:1542347678
ISSN
1362-3028
DOI
10.1080/0026897031000109383
language
English
LU publication?
yes
id
a7db7a94-764e-49c4-b397-95bb4891fbbc (old id 128725)
alternative location
http://www.ingentaconnect.com/content/tandf/tmph/2003/00000101/00000013/art00008;jsessionid=6od03q486g3i.alice
date added to LUP
2007-07-17 10:51:59
date last changed
2018-05-29 12:06:31
@article{a7db7a94-764e-49c4-b397-95bb4891fbbc,
  abstract     = {We have used the density functional B3LYP method to study the effect of hydrogen bonds from the histidine ligand in various haem proteins to carboxyl groups or to the carbonyl backbone. Hydrogen bonds to carbonyl groups (encountered in globins and cytochromes, for example) have a small influence on the geometry and properties of the haem site. However, hydrogen bonds to a carboxyl group (encountered in peroxidases and haem oxidase) may have a profound effect. The results indicate that in the Fe3+ state, this leads to a deprotonation of the histidine ligand, whereas in the Fe2+ state, the proton involved in the hydrogen bond may reside on either histidine or the carboxylate group, depending on the detailed structure of the surroundings. If the histidine is deprotonated, the axial Fe-N bond length decreases by 0.15 Å, whereas the equatorial bond lengths increase. Moreover, the charge on iron and histidine is reduced, as is the spin density on iron. Most importantly, the energy difference between the high and intermediate spin states changes so that whereas the two spin states are degenerate in the Fe2+ state for the protonated histidine, they are degenerate for the Fe3+ state when it is deprotonated. This may facilitate the spin-forbidden binding of dioxygen and peroxide substrates, which takes place for the Fe2+ state in globins but in the Fe3+ state in peroxidases. The reduction potential of the haem group decreases when it hydrogen-bonds to a negatively charged group. The inner-sphere reorganization energy of the Fe2+/Fe3+ transition in a five-coordinate haem complex is ˜30 kJ mol−1, except when the histidine ligand is deprotonated without any hydrogen-bond interaction.},
  author       = {Jensen, Kasper and Ryde, Ulf},
  issn         = {1362-3028},
  language     = {eng},
  number       = {13},
  pages        = {2003--2018},
  publisher    = {Taylor & Francis},
  series       = {Molecular Physics},
  title        = {Importance of proximal hydrogen bonds in haem proteins.},
  url          = {http://dx.doi.org/10.1080/0026897031000109383},
  volume       = {101},
  year         = {2003},
}