Advanced

Theoretical study of the discrimination between O(2) and CO by myoglobin.

Sigfridsson, Emma and Ryde, Ulf LU (2002) In Journal of Inorganic Biochemistry 91(1). p.101-115
Abstract
Combined quantum chemical and molecular mechanics geometry optimisations have been performed on myoglobin without or with O(2) or CO bound to the haem group. The results show that the distal histidine residue is protonated on the N(varepsilon2) atom and forms a hydrogen bond to the haem ligand both in the O(2) and the CO complexes. We have also re-refined the crystal structure of CO-myoglobin by a combined quantum chemical and crystallographic refinement. Thereby, we probably obtain the most accurate available structure of the active site of this complex, showing a Fe-C-O angle of 171 degrees, and Fe-C and C-O bond lengths of 170-171 and 116-117 pm. The resulting structures have been used to calculate the strength of the hydrogen bond... (More)
Combined quantum chemical and molecular mechanics geometry optimisations have been performed on myoglobin without or with O(2) or CO bound to the haem group. The results show that the distal histidine residue is protonated on the N(varepsilon2) atom and forms a hydrogen bond to the haem ligand both in the O(2) and the CO complexes. We have also re-refined the crystal structure of CO-myoglobin by a combined quantum chemical and crystallographic refinement. Thereby, we probably obtain the most accurate available structure of the active site of this complex, showing a Fe-C-O angle of 171 degrees, and Fe-C and C-O bond lengths of 170-171 and 116-117 pm. The resulting structures have been used to calculate the strength of the hydrogen bond between the distal histidine residue and O(2) or CO in the protein. This amounts to 31-33 kJ/mol for O(2) and 2-3 kJ/mol for CO. The difference in hydrogen-bond strength is 21-22 kJ/mol when corrected for entropy effects. This is slightly larger than the observed discrimination between O(2) or CO by myoglobin, 17 kJ/mol. We have also estimated the strain of the active site inside the protein. It is 2-4 kJ/mol larger for the O(2) complex than for the CO complex, independent of which crystal structure the calculations are based on. Together, these results clearly show that myoglobin discriminates between O(2) and CO mainly by electrostatic interactions, rather than by steric strain. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Myoglobin, QC/MM calculations, Quantum refinement, CO/O2 discrimination, Protein strain
in
Journal of Inorganic Biochemistry
volume
91
issue
1
pages
101 - 115
publisher
Elsevier
external identifiers
  • wos:000177141500013
  • pmid:12121767
  • scopus:0037173553
ISSN
1873-3344
DOI
10.1016/S0162-0134(02)00426-9
language
English
LU publication?
yes
id
b60d5bf7-518f-4596-a7af-fd347d6e7e1f (old id 109363)
date added to LUP
2007-07-17 14:11:43
date last changed
2017-08-27 05:37:26
@article{b60d5bf7-518f-4596-a7af-fd347d6e7e1f,
  abstract     = {Combined quantum chemical and molecular mechanics geometry optimisations have been performed on myoglobin without or with O(2) or CO bound to the haem group. The results show that the distal histidine residue is protonated on the N(varepsilon2) atom and forms a hydrogen bond to the haem ligand both in the O(2) and the CO complexes. We have also re-refined the crystal structure of CO-myoglobin by a combined quantum chemical and crystallographic refinement. Thereby, we probably obtain the most accurate available structure of the active site of this complex, showing a Fe-C-O angle of 171 degrees, and Fe-C and C-O bond lengths of 170-171 and 116-117 pm. The resulting structures have been used to calculate the strength of the hydrogen bond between the distal histidine residue and O(2) or CO in the protein. This amounts to 31-33 kJ/mol for O(2) and 2-3 kJ/mol for CO. The difference in hydrogen-bond strength is 21-22 kJ/mol when corrected for entropy effects. This is slightly larger than the observed discrimination between O(2) or CO by myoglobin, 17 kJ/mol. We have also estimated the strain of the active site inside the protein. It is 2-4 kJ/mol larger for the O(2) complex than for the CO complex, independent of which crystal structure the calculations are based on. Together, these results clearly show that myoglobin discriminates between O(2) and CO mainly by electrostatic interactions, rather than by steric strain.},
  author       = {Sigfridsson, Emma and Ryde, Ulf},
  issn         = {1873-3344},
  keyword      = {Myoglobin,QC/MM calculations,Quantum refinement,CO/O2 discrimination,Protein strain},
  language     = {eng},
  number       = {1},
  pages        = {101--115},
  publisher    = {Elsevier},
  series       = {Journal of Inorganic Biochemistry},
  title        = {Theoretical study of the discrimination between O(2) and CO by myoglobin.},
  url          = {http://dx.doi.org/10.1016/S0162-0134(02)00426-9},
  volume       = {91},
  year         = {2002},
}