Thermodynamic and kinetic characterisation of individual haems in multicentre cytochromes c(3)
Thermodynamic and kinetic characterisation of individual haems in multicentre cytochromes c(3)
The characterisation of individual centres in multihaem proteins is difficult due to the similarities in the redox and spectroscopic properties of the centres. NMR has been used successfully to distinguish redox centres and allow the determination of the microscopic thermodynamic parameters in several multihaem cytochromes c3 isolated from different sulphate-reducing bacteria. In this article we show that it is also possible to discriminate the kinetic properties of individual centres in multihaem proteins, if the complete microscopic thermodynamic characterisation is available and the system displays fast intramolecular equilibration in the time scale of the kinetic experiment. The deconvolution of the kinetic traces using a model of thermodynamic control provides a reference rate constant for each haem that does not depend on driving force and can be related to structural factors. The thermodynamic characterisation of three tetrahaem cytochromes and their kinetics of reduction by sodium dithionite are reported in this paper. Thermodynamic and kinetic data were fitted simultaneously to a model to obtain microscopic reduction potentials, haem–haem and haem–proton interacting potentials, and reference rate constants for the haems. The kinetic information obtained for these cytochromes and recently published data for other multihaem cytochromes is discussed with respect to the structural factors that determine the reference rates. The accessibility for the reducing agent seems to play an important role in controlling the kinetic rates, although is clearly not the only factor.
desulfovibrio, functional-properties, redox potentials, angstrom resolution, energy transduction, transfer, vulgaris miyazaki-f, cytochrome c(3), mechanisms, crystal-structure, kinetics, multicentre protein, tetraheme cytochromes, thermodynamic characterisation, electron transfer, desulfovibrio-desulfuricans norway, electron-transfer proteins
1169-1179
Paquete, C.M.
33d20dad-2d71-4a8d-bc17-7e351e4d080d
Turner, D.L.
bc0db1b4-5aa2-4b89-833e-8f0d31499159
Louro, R.O.
5473a453-e54d-4559-968b-abfdc1f36d67
Xavier, A.V.
bc590fd4-ed8f-4ad4-a189-b0fc6b63ff2b
Catarino, T.
02e16379-0fda-4ecd-828c-e10bb0e36502
2007
Paquete, C.M.
33d20dad-2d71-4a8d-bc17-7e351e4d080d
Turner, D.L.
bc0db1b4-5aa2-4b89-833e-8f0d31499159
Louro, R.O.
5473a453-e54d-4559-968b-abfdc1f36d67
Xavier, A.V.
bc590fd4-ed8f-4ad4-a189-b0fc6b63ff2b
Catarino, T.
02e16379-0fda-4ecd-828c-e10bb0e36502
Paquete, C.M., Turner, D.L., Louro, R.O., Xavier, A.V. and Catarino, T.
(2007)
Thermodynamic and kinetic characterisation of individual haems in multicentre cytochromes c(3).
Biochimica et Biophysica Acta (BBA) - Bioenergetics, 1767 (9), .
(doi:10.1016/j.bbabio.2007.06.005).
Abstract
The characterisation of individual centres in multihaem proteins is difficult due to the similarities in the redox and spectroscopic properties of the centres. NMR has been used successfully to distinguish redox centres and allow the determination of the microscopic thermodynamic parameters in several multihaem cytochromes c3 isolated from different sulphate-reducing bacteria. In this article we show that it is also possible to discriminate the kinetic properties of individual centres in multihaem proteins, if the complete microscopic thermodynamic characterisation is available and the system displays fast intramolecular equilibration in the time scale of the kinetic experiment. The deconvolution of the kinetic traces using a model of thermodynamic control provides a reference rate constant for each haem that does not depend on driving force and can be related to structural factors. The thermodynamic characterisation of three tetrahaem cytochromes and their kinetics of reduction by sodium dithionite are reported in this paper. Thermodynamic and kinetic data were fitted simultaneously to a model to obtain microscopic reduction potentials, haem–haem and haem–proton interacting potentials, and reference rate constants for the haems. The kinetic information obtained for these cytochromes and recently published data for other multihaem cytochromes is discussed with respect to the structural factors that determine the reference rates. The accessibility for the reducing agent seems to play an important role in controlling the kinetic rates, although is clearly not the only factor.
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Published date: 2007
Keywords:
desulfovibrio, functional-properties, redox potentials, angstrom resolution, energy transduction, transfer, vulgaris miyazaki-f, cytochrome c(3), mechanisms, crystal-structure, kinetics, multicentre protein, tetraheme cytochromes, thermodynamic characterisation, electron transfer, desulfovibrio-desulfuricans norway, electron-transfer proteins
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Local EPrints ID: 54356
URI: http://eprints.soton.ac.uk/id/eprint/54356
ISSN: 0005-2728
PURE UUID: c4df0c54-96fa-4803-8c04-bd1fe6cfa150
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Date deposited: 31 Jul 2008
Last modified: 15 Mar 2024 10:47
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Contributors
Author:
C.M. Paquete
Author:
D.L. Turner
Author:
R.O. Louro
Author:
A.V. Xavier
Author:
T. Catarino
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