Obtaining ligand geometries from paramagnetic shifts in low-spin haem proteins
Obtaining ligand geometries from paramagnetic shifts in low-spin haem proteins
Previously, the theoretical relationship between paramagnetic chemical shifts and the axial ligands in low-spin haem proteins has been tested extensively in haems b and c with His, Met, and cyanide ligands. Variations in the electronic structure of the haem and the magnetic susceptibility tensors have been shown to depend primarily on the axial ligand geometry, and the shifts of haem substituents have been used to obtain the first structural information for several cytochromes. Recently, the database of assigned spectra for bis-His haems has been extended sufficiently for an empirical equation to be produced for treating H-1 NMR data from haem methyl groups at 298 K. However, the database used contains large systematic deviations and the form of the equation leads to systematic errors in the ligand geometries. This article describes the link with the semi-empirical methods used previously and provides a set of corrected empirical parameters as well as an improved equation. The possibilities for generalising the empirical method to account for ligands other than His and temperatures other than 298 K are discussed.
haem protein, nuclear magnetic resonance, paramagnetic shift, ligand
geometryheme electronic-structure, desulfovibrio-desulfuricans atcc-27774, nuclear magnetic-resonance, cytochrome c(3), methylophilus-methylotrophus, angstrom resolution, axial ligands, c-13nmr, desulfuromonas-acetoxidans, vulgaris hildenborough
328-332
Turner, D. L.
158980fd-3487-480b-baba-15102dfb64b4
1 June 2000
Turner, D. L.
158980fd-3487-480b-baba-15102dfb64b4
Turner, D. L.
(2000)
Obtaining ligand geometries from paramagnetic shifts in low-spin haem proteins.
Journal of Biological Inorganic Chemistry, 5 (3), .
Abstract
Previously, the theoretical relationship between paramagnetic chemical shifts and the axial ligands in low-spin haem proteins has been tested extensively in haems b and c with His, Met, and cyanide ligands. Variations in the electronic structure of the haem and the magnetic susceptibility tensors have been shown to depend primarily on the axial ligand geometry, and the shifts of haem substituents have been used to obtain the first structural information for several cytochromes. Recently, the database of assigned spectra for bis-His haems has been extended sufficiently for an empirical equation to be produced for treating H-1 NMR data from haem methyl groups at 298 K. However, the database used contains large systematic deviations and the form of the equation leads to systematic errors in the ligand geometries. This article describes the link with the semi-empirical methods used previously and provides a set of corrected empirical parameters as well as an improved equation. The possibilities for generalising the empirical method to account for ligands other than His and temperatures other than 298 K are discussed.
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Published date: 1 June 2000
Keywords:
haem protein, nuclear magnetic resonance, paramagnetic shift, ligand
geometryheme electronic-structure, desulfovibrio-desulfuricans atcc-27774, nuclear magnetic-resonance, cytochrome c(3), methylophilus-methylotrophus, angstrom resolution, axial ligands, c-13nmr, desulfuromonas-acetoxidans, vulgaris hildenborough
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Local EPrints ID: 18943
URI: http://eprints.soton.ac.uk/id/eprint/18943
PURE UUID: 7119f5fb-006c-4acd-9411-e49ae0e85bb1
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Date deposited: 19 Jan 2006
Last modified: 08 Jan 2022 18:50
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Author:
D. L. Turner
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