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Theoretical study of structure of catalytic copper site in nitrite reductase

Källrot, Niklas LU ; Nilsson, Kristina LU ; Rasmussen, Torben LU and Ryde, Ulf LU (2005) In International Journal of Quantum Chemistry 102(5). p.520-541
Abstract
The catalytic copper site in nitrite reductase contains a Cu2+ ion bound to three histidine (His) ligands and a solvent molecule. Sites from various sources show a conspicuous variation in the structure. In some proteins, it is close to tetrahedral (even more so than are blue copper proteins), whereas in other proteins, it has a structure more similar to that expected for a type 2 copper site. We have studied this site with a number of theoretical methods, ranging from vacuum optimizations, combined quantum and molecular mechanics (QM/MM) optimization, quantum refinement (X-ray crystallography supplemented by quantum chemical calculations), and accurate energy calculations. We show that the difference in the structure arises from a... (More)
The catalytic copper site in nitrite reductase contains a Cu2+ ion bound to three histidine (His) ligands and a solvent molecule. Sites from various sources show a conspicuous variation in the structure. In some proteins, it is close to tetrahedral (even more so than are blue copper proteins), whereas in other proteins, it has a structure more similar to that expected for a type 2 copper site. We have studied this site with a number of theoretical methods, ranging from vacuum optimizations, combined quantum and molecular mechanics (QM/MM) optimization, quantum refinement (X-ray crystallography supplemented by quantum chemical calculations), and accurate energy calculations. We show that the difference in the structure arises from a movement of the solvent molecule and that this movement is determined by a compromise between its hydrogen bond interactions and the intrinsic preferences of the copper site. If the solvent molecule is deprotonated, the two structures have a similar energy, whereas if it is protonated, the more tetrahedral structure is energetically favorable. Neither of the structures involves a pi interaction as in the blue copper proteins; instead, both are strongly distorted tetragonal structures with sigma bonds to all four ligands. We have also examined the position of hydrogen atoms shared between second-sphere carboxylate groups and the first-sphere solvent molecule and one of the His ligands. In the oxidized state, the structure with the solvent deprotonate(d) but the His residue protonated seems to be most stable. (c) 2004 Wiley Periodicals, Inc. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
International Journal of Quantum Chemistry
volume
102
issue
5
pages
520 - 541
publisher
John Wiley & Sons
external identifiers
  • wos:000228227700007
  • scopus:17644424332
ISSN
0020-7608
DOI
10.1002/qua.20386
language
English
LU publication?
yes
id
2a7e4d98-4603-4133-9527-d68081cac97a (old id 152767)
date added to LUP
2007-07-17 11:07:43
date last changed
2017-04-23 03:31:47
@article{2a7e4d98-4603-4133-9527-d68081cac97a,
  abstract     = {The catalytic copper site in nitrite reductase contains a Cu2+ ion bound to three histidine (His) ligands and a solvent molecule. Sites from various sources show a conspicuous variation in the structure. In some proteins, it is close to tetrahedral (even more so than are blue copper proteins), whereas in other proteins, it has a structure more similar to that expected for a type 2 copper site. We have studied this site with a number of theoretical methods, ranging from vacuum optimizations, combined quantum and molecular mechanics (QM/MM) optimization, quantum refinement (X-ray crystallography supplemented by quantum chemical calculations), and accurate energy calculations. We show that the difference in the structure arises from a movement of the solvent molecule and that this movement is determined by a compromise between its hydrogen bond interactions and the intrinsic preferences of the copper site. If the solvent molecule is deprotonated, the two structures have a similar energy, whereas if it is protonated, the more tetrahedral structure is energetically favorable. Neither of the structures involves a pi interaction as in the blue copper proteins; instead, both are strongly distorted tetragonal structures with sigma bonds to all four ligands. We have also examined the position of hydrogen atoms shared between second-sphere carboxylate groups and the first-sphere solvent molecule and one of the His ligands. In the oxidized state, the structure with the solvent deprotonate(d) but the His residue protonated seems to be most stable. (c) 2004 Wiley Periodicals, Inc.},
  author       = {Källrot, Niklas and Nilsson, Kristina and Rasmussen, Torben and Ryde, Ulf},
  issn         = {0020-7608},
  language     = {eng},
  number       = {5},
  pages        = {520--541},
  publisher    = {John Wiley & Sons},
  series       = {International Journal of Quantum Chemistry},
  title        = {Theoretical study of structure of catalytic copper site in nitrite reductase},
  url          = {http://dx.doi.org/10.1002/qua.20386},
  volume       = {102},
  year         = {2005},
}