On the role of the axial ligand in heme proteins: a theoretical study
(2004) In Journal of Biological Inorganic Chemistry 9(2). p.203-223- Abstract
- We present a systematic investigation of how the axial ligand in heme proteins influences the geometry, electronic structure, and spin states of the active site, and the energies of the reaction cycles. Using the density functional B3LYP method and medium-sized basis sets, we have compared models with His, His+Asp, Cys, Tyr, and Tyr+Arg as found in myoglobin and hemoglobin, peroxidases, cytochrome P450, and heme catalases, respectively. We have studied 12 reactants and intermediates of the reaction cycles of these enzymes, including complexes with H2O, OH-, O2-, CH3OH, O-2, H2O2, and HO2- in various formal oxidation states of the iron ion (II to V). The results show that His gives similar to0.6 V higher reduction potentials than the other... (More)
- We present a systematic investigation of how the axial ligand in heme proteins influences the geometry, electronic structure, and spin states of the active site, and the energies of the reaction cycles. Using the density functional B3LYP method and medium-sized basis sets, we have compared models with His, His+Asp, Cys, Tyr, and Tyr+Arg as found in myoglobin and hemoglobin, peroxidases, cytochrome P450, and heme catalases, respectively. We have studied 12 reactants and intermediates of the reaction cycles of these enzymes, including complexes with H2O, OH-, O2-, CH3OH, O-2, H2O2, and HO2- in various formal oxidation states of the iron ion (II to V). The results show that His gives similar to0.6 V higher reduction potentials than the other ligands. In particular, it is harder to reduce and protonate the O-2 complex with His than with the other ligands, in accordance with the O-2 carrier function of globins and the oxidative chemistry of the other proteins. For most properties, the trend Cys<Tyr<Tyr+Arg<His+Asp<His is found, reflecting the donor capacity of the various ligands. Thus, it is easier to reduce compound I with a His+Asp ligand than with a Cys ligand, in accordance with the one-electron chemistry of peroxidases and the hydroxylation reactions of cytochromes P450. However, the Tyr complexes have an unusually low affinity for all neutral ligands, giving them a slightly enhanced driving force in the oxidation of H2O2 by compound I. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/139701
- author
- Rydberg, Patrik
LU
; Sigfridsson, Emma
and Ryde, Ulf
LU
- organization
- publishing date
- 2004
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Journal of Biological Inorganic Chemistry
- volume
- 9
- issue
- 2
- pages
- 203 - 223
- publisher
- Springer
- external identifiers
-
- wos:000189274500010
- pmid:14727167
- scopus:1542620864
- pmid:14727167
- ISSN
- 1432-1327
- DOI
- 10.1007/s00775-003-0515-y
- 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
- 3ee040ef-1aed-40be-acdd-55b332ed60bd (old id 139701)
- date added to LUP
- 2016-04-01 12:02:54
- date last changed
- 2023-01-24 02:30:56
@article{3ee040ef-1aed-40be-acdd-55b332ed60bd, abstract = {{We present a systematic investigation of how the axial ligand in heme proteins influences the geometry, electronic structure, and spin states of the active site, and the energies of the reaction cycles. Using the density functional B3LYP method and medium-sized basis sets, we have compared models with His, His+Asp, Cys, Tyr, and Tyr+Arg as found in myoglobin and hemoglobin, peroxidases, cytochrome P450, and heme catalases, respectively. We have studied 12 reactants and intermediates of the reaction cycles of these enzymes, including complexes with H2O, OH-, O2-, CH3OH, O-2, H2O2, and HO2- in various formal oxidation states of the iron ion (II to V). The results show that His gives similar to0.6 V higher reduction potentials than the other ligands. In particular, it is harder to reduce and protonate the O-2 complex with His than with the other ligands, in accordance with the O-2 carrier function of globins and the oxidative chemistry of the other proteins. For most properties, the trend Cys<Tyr<Tyr+Arg<His+Asp<His is found, reflecting the donor capacity of the various ligands. Thus, it is easier to reduce compound I with a His+Asp ligand than with a Cys ligand, in accordance with the one-electron chemistry of peroxidases and the hydroxylation reactions of cytochromes P450. However, the Tyr complexes have an unusually low affinity for all neutral ligands, giving them a slightly enhanced driving force in the oxidation of H2O2 by compound I.}}, author = {{Rydberg, Patrik and Sigfridsson, Emma and Ryde, Ulf}}, issn = {{1432-1327}}, language = {{eng}}, number = {{2}}, pages = {{203--223}}, publisher = {{Springer}}, series = {{Journal of Biological Inorganic Chemistry}}, title = {{On the role of the axial ligand in heme proteins: a theoretical study}}, url = {{https://lup.lub.lu.se/search/files/135492433/64_p450.pdf}}, doi = {{10.1007/s00775-003-0515-y}}, volume = {{9}}, year = {{2004}}, }