Proton release due to manganese binding and oxidation in modified bacterial reaction centers

L. Kálmán, M. C. Thielges, Joann Williams, James Allen

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The pH dependence of binding and oxidation of Mn2+ in highly oxidizing reaction centers with designed metal-binding sites was characterized by light-minus-dark optical difference spectroscopy and direct measurements of proton uptake/release. These mutants bind a Mn2+ ion that can efficiently transfer an electron to the oxidized bacteriochlorophyll dimer, as described earlier [Thielges et al. (2005) Biochemistry 44, 7389-7394]. The dissociation constant, KD, significantly increased with decreasing pH. The pH dependence of KD between pH 7 and pH 8 was consistent with the binding of Mn2+ being stabilized by the electrostatic release of two protons. The strong pH dependence of proton release upon Mn2+ binding, with a maximal release of 1.4 H+ per reaction center, was interpreted as being a result of a shift in the pKa values of the coordinating residues and possibly other nearby residues. A small amount of proton release associated with Mn2+ oxidation was observed upon illumination. These results show that functional metal-binding sites can be incorporated into proteins upon consideration of both the metal coordination and protonation states of the ligands.

Original languageEnglish (US)
Pages (from-to)13266-13273
Number of pages8
JournalBiochemistry
Volume44
Issue number40
DOIs
StatePublished - Oct 11 2005

Fingerprint

Manganese
Protons
Oxidation
Metals
Binding Sites
Bacteriochlorophylls
Biochemistry
Protonation
Dimers
Electrostatics
Lighting
Spectroscopy
Ions
Ligands
Static Electricity
Electrons
Spectrum Analysis
Light
Proteins

ASJC Scopus subject areas

  • Biochemistry

Cite this

Proton release due to manganese binding and oxidation in modified bacterial reaction centers. / Kálmán, L.; Thielges, M. C.; Williams, Joann; Allen, James.

In: Biochemistry, Vol. 44, No. 40, 11.10.2005, p. 13266-13273.

Research output: Contribution to journalArticle

@article{8cbee00be217400f9296626ff3bc1c73,
title = "Proton release due to manganese binding and oxidation in modified bacterial reaction centers",
abstract = "The pH dependence of binding and oxidation of Mn2+ in highly oxidizing reaction centers with designed metal-binding sites was characterized by light-minus-dark optical difference spectroscopy and direct measurements of proton uptake/release. These mutants bind a Mn2+ ion that can efficiently transfer an electron to the oxidized bacteriochlorophyll dimer, as described earlier [Thielges et al. (2005) Biochemistry 44, 7389-7394]. The dissociation constant, KD, significantly increased with decreasing pH. The pH dependence of KD between pH 7 and pH 8 was consistent with the binding of Mn2+ being stabilized by the electrostatic release of two protons. The strong pH dependence of proton release upon Mn2+ binding, with a maximal release of 1.4 H+ per reaction center, was interpreted as being a result of a shift in the pKa values of the coordinating residues and possibly other nearby residues. A small amount of proton release associated with Mn2+ oxidation was observed upon illumination. These results show that functional metal-binding sites can be incorporated into proteins upon consideration of both the metal coordination and protonation states of the ligands.",
author = "L. K{\'a}lm{\'a}n and Thielges, {M. C.} and Joann Williams and James Allen",
year = "2005",
month = "10",
day = "11",
doi = "10.1021/bi051149w",
language = "English (US)",
volume = "44",
pages = "13266--13273",
journal = "Biochemistry",
issn = "0006-2960",
publisher = "American Chemical Society",
number = "40",

}

TY - JOUR

T1 - Proton release due to manganese binding and oxidation in modified bacterial reaction centers

AU - Kálmán, L.

AU - Thielges, M. C.

AU - Williams, Joann

AU - Allen, James

PY - 2005/10/11

Y1 - 2005/10/11

N2 - The pH dependence of binding and oxidation of Mn2+ in highly oxidizing reaction centers with designed metal-binding sites was characterized by light-minus-dark optical difference spectroscopy and direct measurements of proton uptake/release. These mutants bind a Mn2+ ion that can efficiently transfer an electron to the oxidized bacteriochlorophyll dimer, as described earlier [Thielges et al. (2005) Biochemistry 44, 7389-7394]. The dissociation constant, KD, significantly increased with decreasing pH. The pH dependence of KD between pH 7 and pH 8 was consistent with the binding of Mn2+ being stabilized by the electrostatic release of two protons. The strong pH dependence of proton release upon Mn2+ binding, with a maximal release of 1.4 H+ per reaction center, was interpreted as being a result of a shift in the pKa values of the coordinating residues and possibly other nearby residues. A small amount of proton release associated with Mn2+ oxidation was observed upon illumination. These results show that functional metal-binding sites can be incorporated into proteins upon consideration of both the metal coordination and protonation states of the ligands.

AB - The pH dependence of binding and oxidation of Mn2+ in highly oxidizing reaction centers with designed metal-binding sites was characterized by light-minus-dark optical difference spectroscopy and direct measurements of proton uptake/release. These mutants bind a Mn2+ ion that can efficiently transfer an electron to the oxidized bacteriochlorophyll dimer, as described earlier [Thielges et al. (2005) Biochemistry 44, 7389-7394]. The dissociation constant, KD, significantly increased with decreasing pH. The pH dependence of KD between pH 7 and pH 8 was consistent with the binding of Mn2+ being stabilized by the electrostatic release of two protons. The strong pH dependence of proton release upon Mn2+ binding, with a maximal release of 1.4 H+ per reaction center, was interpreted as being a result of a shift in the pKa values of the coordinating residues and possibly other nearby residues. A small amount of proton release associated with Mn2+ oxidation was observed upon illumination. These results show that functional metal-binding sites can be incorporated into proteins upon consideration of both the metal coordination and protonation states of the ligands.

UR - http://www.scopus.com/inward/record.url?scp=26444458800&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=26444458800&partnerID=8YFLogxK

U2 - 10.1021/bi051149w

DO - 10.1021/bi051149w

M3 - Article

C2 - 16201752

AN - SCOPUS:26444458800

VL - 44

SP - 13266

EP - 13273

JO - Biochemistry

JF - Biochemistry

SN - 0006-2960

IS - 40

ER -