Electron transfer patterns of the di-heme protein cytochrome c(4) from Pseudomonas stutzeri

Anders Christer Raffalt, L. Schmidt, Hans Erik Mølager Christensen, Qijin Chi, Jens Ulstrup

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

We report kinetic data for the two-step electron transfer (ET) oxidation and reduction of the two-domain di-heme redox protein Pseudomonas stutzeri cytochrome (cyt) c(4) by [Co(bipy)(3)](2- 3-) (bipy = 2,2'-bipyridine). Following earlier reports, the data accord with both bi- and tri-exponential kinetics. A complete kinetic scheme includes both "cooperative" intermolecular ET between each heme group and the external reaction partner, and intramolecular ET between the two heme groups. A now data analysis scheme shows unequivocally that two-ET oxidation and reduction of P. stutzeri cyt c(4) is entirely dominated by intermolecular ET between the heme groups and the external reaction partner in the ms time range, with virtually no contribution from intramolecular interheme ET in this time range. This is in striking contrast to two-ET electrochemical oxidation or reduction of P. stutzeri cyt c(4) for which fast, ms to sub-ms intramolecular interheme ET is a crucial step. The rate constant dependence on the solvent viscosity has disclosed strong coupling to both a (set of) frictionally damped solvent/protein nuclear modes and intramolecular friction-less "ballistic" modes, indicative of notable protein structural mobility in the overall two-ET process. We suggest that conformational protein mobility blocks intramolecular interheme ET in bulk homogeneous solution but triggers opening of this gated ET channel in the electrochemical environment or in the membrane environment of natural respiratory cyt c(4) function.
Original languageEnglish
JournalJournal of Inorganic Biochemistry
Volume103
Issue number5
Pages (from-to)717-722
ISSN0162-0134
DOIs
Publication statusPublished - 2009

Keywords

  • Cytochrome c(4)
  • Intramolecular electron transfer

Cite this

Raffalt, Anders Christer ; Schmidt, L. ; Christensen, Hans Erik Mølager ; Chi, Qijin ; Ulstrup, Jens. / Electron transfer patterns of the di-heme protein cytochrome c(4) from Pseudomonas stutzeri. In: Journal of Inorganic Biochemistry. 2009 ; Vol. 103, No. 5. pp. 717-722.
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abstract = "We report kinetic data for the two-step electron transfer (ET) oxidation and reduction of the two-domain di-heme redox protein Pseudomonas stutzeri cytochrome (cyt) c(4) by [Co(bipy)(3)](2- 3-) (bipy = 2,2'-bipyridine). Following earlier reports, the data accord with both bi- and tri-exponential kinetics. A complete kinetic scheme includes both {"}cooperative{"} intermolecular ET between each heme group and the external reaction partner, and intramolecular ET between the two heme groups. A now data analysis scheme shows unequivocally that two-ET oxidation and reduction of P. stutzeri cyt c(4) is entirely dominated by intermolecular ET between the heme groups and the external reaction partner in the ms time range, with virtually no contribution from intramolecular interheme ET in this time range. This is in striking contrast to two-ET electrochemical oxidation or reduction of P. stutzeri cyt c(4) for which fast, ms to sub-ms intramolecular interheme ET is a crucial step. The rate constant dependence on the solvent viscosity has disclosed strong coupling to both a (set of) frictionally damped solvent/protein nuclear modes and intramolecular friction-less {"}ballistic{"} modes, indicative of notable protein structural mobility in the overall two-ET process. We suggest that conformational protein mobility blocks intramolecular interheme ET in bulk homogeneous solution but triggers opening of this gated ET channel in the electrochemical environment or in the membrane environment of natural respiratory cyt c(4) function.",
keywords = "Cytochrome c(4), Intramolecular electron transfer",
author = "Raffalt, {Anders Christer} and L. Schmidt and Christensen, {Hans Erik M{\o}lager} and Qijin Chi and Jens Ulstrup",
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Electron transfer patterns of the di-heme protein cytochrome c(4) from Pseudomonas stutzeri. / Raffalt, Anders Christer; Schmidt, L.; Christensen, Hans Erik Mølager; Chi, Qijin; Ulstrup, Jens.

In: Journal of Inorganic Biochemistry, Vol. 103, No. 5, 2009, p. 717-722.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Electron transfer patterns of the di-heme protein cytochrome c(4) from Pseudomonas stutzeri

AU - Raffalt, Anders Christer

AU - Schmidt, L.

AU - Christensen, Hans Erik Mølager

AU - Chi, Qijin

AU - Ulstrup, Jens

PY - 2009

Y1 - 2009

N2 - We report kinetic data for the two-step electron transfer (ET) oxidation and reduction of the two-domain di-heme redox protein Pseudomonas stutzeri cytochrome (cyt) c(4) by [Co(bipy)(3)](2- 3-) (bipy = 2,2'-bipyridine). Following earlier reports, the data accord with both bi- and tri-exponential kinetics. A complete kinetic scheme includes both "cooperative" intermolecular ET between each heme group and the external reaction partner, and intramolecular ET between the two heme groups. A now data analysis scheme shows unequivocally that two-ET oxidation and reduction of P. stutzeri cyt c(4) is entirely dominated by intermolecular ET between the heme groups and the external reaction partner in the ms time range, with virtually no contribution from intramolecular interheme ET in this time range. This is in striking contrast to two-ET electrochemical oxidation or reduction of P. stutzeri cyt c(4) for which fast, ms to sub-ms intramolecular interheme ET is a crucial step. The rate constant dependence on the solvent viscosity has disclosed strong coupling to both a (set of) frictionally damped solvent/protein nuclear modes and intramolecular friction-less "ballistic" modes, indicative of notable protein structural mobility in the overall two-ET process. We suggest that conformational protein mobility blocks intramolecular interheme ET in bulk homogeneous solution but triggers opening of this gated ET channel in the electrochemical environment or in the membrane environment of natural respiratory cyt c(4) function.

AB - We report kinetic data for the two-step electron transfer (ET) oxidation and reduction of the two-domain di-heme redox protein Pseudomonas stutzeri cytochrome (cyt) c(4) by [Co(bipy)(3)](2- 3-) (bipy = 2,2'-bipyridine). Following earlier reports, the data accord with both bi- and tri-exponential kinetics. A complete kinetic scheme includes both "cooperative" intermolecular ET between each heme group and the external reaction partner, and intramolecular ET between the two heme groups. A now data analysis scheme shows unequivocally that two-ET oxidation and reduction of P. stutzeri cyt c(4) is entirely dominated by intermolecular ET between the heme groups and the external reaction partner in the ms time range, with virtually no contribution from intramolecular interheme ET in this time range. This is in striking contrast to two-ET electrochemical oxidation or reduction of P. stutzeri cyt c(4) for which fast, ms to sub-ms intramolecular interheme ET is a crucial step. The rate constant dependence on the solvent viscosity has disclosed strong coupling to both a (set of) frictionally damped solvent/protein nuclear modes and intramolecular friction-less "ballistic" modes, indicative of notable protein structural mobility in the overall two-ET process. We suggest that conformational protein mobility blocks intramolecular interheme ET in bulk homogeneous solution but triggers opening of this gated ET channel in the electrochemical environment or in the membrane environment of natural respiratory cyt c(4) function.

KW - Cytochrome c(4)

KW - Intramolecular electron transfer

U2 - 10.1016/j.jinorgbio.2009.01.004

DO - 10.1016/j.jinorgbio.2009.01.004

M3 - Journal article

VL - 103

SP - 717

EP - 722

JO - Journal of Inorganic Biochemistry

JF - Journal of Inorganic Biochemistry

SN - 0162-0134

IS - 5

ER -