Reduction of the oxidized bacteriochlorophyll dimer in reaction centers by ferrocene is dependent upon the driving force

László Kálmán, Arlene L M Haffa, JoAnn C. Williams, Neal W. Woodbury, James Paul Allen

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The rates of electron transfer from ferrocene to the oxidized bacteriochlorophyll dimer, P, in reaction centers from the purple photosynthetic bacterium Rhodobacter sphaeroides, were measured for a series of mutants in which the P/P+ midpoint potentials range from 410 to 765 mV (Lin et al. Proc. Natl. Acad. Sci. USA 1994; 91: 10265-10269). The observed rate constant for each mutant was found to be linearly dependent upon the ferrocene concentration up to 50 μM. The electron transfer is described as a second order reaction with rate constants increasing from 1.5 to 35 × 10 6 M-1.s-1 with increasing P/P+ midpoint potential. This dependence was tested for three additional mutants, each of which exhibits a pH dependence of the P/P+ midpoint potential due to an electrostatic interaction with an introduced carboxylic group (Williams et al. Biochemistry 2001; 40: 15403-15407). For these mutants, the pH dependence of the bimolecular rate constants followed a sigmoidal pattern that could be described with a Henderson-Hasselbalch equation, attributable to the change of the free energy difference for the reaction due to deprotonation of the introduced carboxylic side chains.

Original languageEnglish
Pages (from-to)205-211
Number of pages7
JournalJournal of Porphyrins and Phthalocyanines
Volume11
Issue number3-4
Publication statusPublished - 2007

Fingerprint

Bacteriochlorophylls
Dimers
Rate constants
Deprotonation
Biochemistry
Electrons
Coulomb interactions
Free energy
Bacteria
ferrocene

Keywords

  • Bacterial reaction center
  • Bimolecular electron transfer
  • Electrostatic interactions
  • Rhodobacter sphaeroides
  • Secondary electron donor

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Reduction of the oxidized bacteriochlorophyll dimer in reaction centers by ferrocene is dependent upon the driving force. / Kálmán, László; Haffa, Arlene L M; Williams, JoAnn C.; Woodbury, Neal W.; Allen, James Paul.

In: Journal of Porphyrins and Phthalocyanines, Vol. 11, No. 3-4, 2007, p. 205-211.

Research output: Contribution to journalArticle

Kálmán, László ; Haffa, Arlene L M ; Williams, JoAnn C. ; Woodbury, Neal W. ; Allen, James Paul. / Reduction of the oxidized bacteriochlorophyll dimer in reaction centers by ferrocene is dependent upon the driving force. In: Journal of Porphyrins and Phthalocyanines. 2007 ; Vol. 11, No. 3-4. pp. 205-211.
@article{218086003af8481889e221231431b9fb,
title = "Reduction of the oxidized bacteriochlorophyll dimer in reaction centers by ferrocene is dependent upon the driving force",
abstract = "The rates of electron transfer from ferrocene to the oxidized bacteriochlorophyll dimer, P, in reaction centers from the purple photosynthetic bacterium Rhodobacter sphaeroides, were measured for a series of mutants in which the P/P+ midpoint potentials range from 410 to 765 mV (Lin et al. Proc. Natl. Acad. Sci. USA 1994; 91: 10265-10269). The observed rate constant for each mutant was found to be linearly dependent upon the ferrocene concentration up to 50 μM. The electron transfer is described as a second order reaction with rate constants increasing from 1.5 to 35 × 10 6 M-1.s-1 with increasing P/P+ midpoint potential. This dependence was tested for three additional mutants, each of which exhibits a pH dependence of the P/P+ midpoint potential due to an electrostatic interaction with an introduced carboxylic group (Williams et al. Biochemistry 2001; 40: 15403-15407). For these mutants, the pH dependence of the bimolecular rate constants followed a sigmoidal pattern that could be described with a Henderson-Hasselbalch equation, attributable to the change of the free energy difference for the reaction due to deprotonation of the introduced carboxylic side chains.",
keywords = "Bacterial reaction center, Bimolecular electron transfer, Electrostatic interactions, Rhodobacter sphaeroides, Secondary electron donor",
author = "L{\'a}szl{\'o} K{\'a}lm{\'a}n and Haffa, {Arlene L M} and Williams, {JoAnn C.} and Woodbury, {Neal W.} and Allen, {James Paul}",
year = "2007",
language = "English",
volume = "11",
pages = "205--211",
journal = "Journal of Porphyrins and Phthalocyanines",
issn = "1088-4246",
publisher = "Society of Porphyrins and Phthalocyanines (SPP)",
number = "3-4",

}

TY - JOUR

T1 - Reduction of the oxidized bacteriochlorophyll dimer in reaction centers by ferrocene is dependent upon the driving force

AU - Kálmán, László

AU - Haffa, Arlene L M

AU - Williams, JoAnn C.

AU - Woodbury, Neal W.

AU - Allen, James Paul

PY - 2007

Y1 - 2007

N2 - The rates of electron transfer from ferrocene to the oxidized bacteriochlorophyll dimer, P, in reaction centers from the purple photosynthetic bacterium Rhodobacter sphaeroides, were measured for a series of mutants in which the P/P+ midpoint potentials range from 410 to 765 mV (Lin et al. Proc. Natl. Acad. Sci. USA 1994; 91: 10265-10269). The observed rate constant for each mutant was found to be linearly dependent upon the ferrocene concentration up to 50 μM. The electron transfer is described as a second order reaction with rate constants increasing from 1.5 to 35 × 10 6 M-1.s-1 with increasing P/P+ midpoint potential. This dependence was tested for three additional mutants, each of which exhibits a pH dependence of the P/P+ midpoint potential due to an electrostatic interaction with an introduced carboxylic group (Williams et al. Biochemistry 2001; 40: 15403-15407). For these mutants, the pH dependence of the bimolecular rate constants followed a sigmoidal pattern that could be described with a Henderson-Hasselbalch equation, attributable to the change of the free energy difference for the reaction due to deprotonation of the introduced carboxylic side chains.

AB - The rates of electron transfer from ferrocene to the oxidized bacteriochlorophyll dimer, P, in reaction centers from the purple photosynthetic bacterium Rhodobacter sphaeroides, were measured for a series of mutants in which the P/P+ midpoint potentials range from 410 to 765 mV (Lin et al. Proc. Natl. Acad. Sci. USA 1994; 91: 10265-10269). The observed rate constant for each mutant was found to be linearly dependent upon the ferrocene concentration up to 50 μM. The electron transfer is described as a second order reaction with rate constants increasing from 1.5 to 35 × 10 6 M-1.s-1 with increasing P/P+ midpoint potential. This dependence was tested for three additional mutants, each of which exhibits a pH dependence of the P/P+ midpoint potential due to an electrostatic interaction with an introduced carboxylic group (Williams et al. Biochemistry 2001; 40: 15403-15407). For these mutants, the pH dependence of the bimolecular rate constants followed a sigmoidal pattern that could be described with a Henderson-Hasselbalch equation, attributable to the change of the free energy difference for the reaction due to deprotonation of the introduced carboxylic side chains.

KW - Bacterial reaction center

KW - Bimolecular electron transfer

KW - Electrostatic interactions

KW - Rhodobacter sphaeroides

KW - Secondary electron donor

UR - http://www.scopus.com/inward/record.url?scp=34249318045&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=34249318045&partnerID=8YFLogxK

M3 - Article

VL - 11

SP - 205

EP - 211

JO - Journal of Porphyrins and Phthalocyanines

JF - Journal of Porphyrins and Phthalocyanines

SN - 1088-4246

IS - 3-4

ER -