Metal Cations Induced alpha beta-BChl a Heterogeneity in LH1 as Revealed by Temperature-Dependent Fluorescence Splitting

Fei Ma, Long-Jiang Yu, Manuel J. Llansola-Portoles, Bruno Robert, Zheng-Yu Wang-Otomo, Rienk van Grondelle

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Two spectral forms of the core light-harvesting complex (LH1) of the purple bacterium Thermochromatium (Tch.) tepidum, the native Ca2+-binding and the Ba2+-substituted one, exhibit different fluorescence (FL) emission spectra at low temperature (T). While Ca-LH1 exhibits one emission band, an unusual splitting of the fluorescence is observed for Ba-LH1. These two sub-bands display the same spectral-width dependence according to T, but their intensity evolves differently with T. Based on the crystal structures, we propose that the FL splitting originates from a large alpha beta-BChl a transition energy heterogeneity, approximate to 600 cm(-1), which is much larger compared with other LH1 and LH2 complexes (80-200 cm(-1)). This large heterogeneity is induced by the inhomogeneous Coulomb (and possibly hydrogen-bonding) interactions exerted by Ba2+. The energy levels of the two LH1s were compared using exciton calculations in combination with Redfield theory. To simulate the FL splitting, an electronic transition containing two resonant bands was considered. This work shows how metal cations incorporated into the polypeptide modulate the electronic properties of BChl a aggregates.
Original languageEnglish
Pages (from-to)2295-2301
JournalChemPhysChem
Volume18
Issue number16
DOIs
Publication statusPublished - 18 Aug 2017

Keywords

  • core light-harvesting complex
  • fluorescence spectroscopy
  • Redfield theory
  • transition energy
  • alpha beta-BChl a heterogeneity

Cite this

Ma, Fei ; Yu, Long-Jiang ; Llansola-Portoles, Manuel J. ; Robert, Bruno ; Wang-Otomo, Zheng-Yu ; van Grondelle, Rienk. / Metal Cations Induced alpha beta-BChl a Heterogeneity in LH1 as Revealed by Temperature-Dependent Fluorescence Splitting. In: ChemPhysChem. 2017 ; Vol. 18, No. 16. pp. 2295-2301.
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abstract = "Two spectral forms of the core light-harvesting complex (LH1) of the purple bacterium Thermochromatium (Tch.) tepidum, the native Ca2+-binding and the Ba2+-substituted one, exhibit different fluorescence (FL) emission spectra at low temperature (T). While Ca-LH1 exhibits one emission band, an unusual splitting of the fluorescence is observed for Ba-LH1. These two sub-bands display the same spectral-width dependence according to T, but their intensity evolves differently with T. Based on the crystal structures, we propose that the FL splitting originates from a large alpha beta-BChl a transition energy heterogeneity, approximate to 600 cm(-1), which is much larger compared with other LH1 and LH2 complexes (80-200 cm(-1)). This large heterogeneity is induced by the inhomogeneous Coulomb (and possibly hydrogen-bonding) interactions exerted by Ba2+. The energy levels of the two LH1s were compared using exciton calculations in combination with Redfield theory. To simulate the FL splitting, an electronic transition containing two resonant bands was considered. This work shows how metal cations incorporated into the polypeptide modulate the electronic properties of BChl a aggregates.",
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Metal Cations Induced alpha beta-BChl a Heterogeneity in LH1 as Revealed by Temperature-Dependent Fluorescence Splitting. / Ma, Fei; Yu, Long-Jiang; Llansola-Portoles, Manuel J.; Robert, Bruno; Wang-Otomo, Zheng-Yu; van Grondelle, Rienk.

In: ChemPhysChem, Vol. 18, No. 16, 18.08.2017, p. 2295-2301.

Research output: Contribution to JournalArticleAcademicpeer-review

TY - JOUR

T1 - Metal Cations Induced alpha beta-BChl a Heterogeneity in LH1 as Revealed by Temperature-Dependent Fluorescence Splitting

AU - Ma, Fei

AU - Yu, Long-Jiang

AU - Llansola-Portoles, Manuel J.

AU - Robert, Bruno

AU - Wang-Otomo, Zheng-Yu

AU - van Grondelle, Rienk

PY - 2017/8/18

Y1 - 2017/8/18

N2 - Two spectral forms of the core light-harvesting complex (LH1) of the purple bacterium Thermochromatium (Tch.) tepidum, the native Ca2+-binding and the Ba2+-substituted one, exhibit different fluorescence (FL) emission spectra at low temperature (T). While Ca-LH1 exhibits one emission band, an unusual splitting of the fluorescence is observed for Ba-LH1. These two sub-bands display the same spectral-width dependence according to T, but their intensity evolves differently with T. Based on the crystal structures, we propose that the FL splitting originates from a large alpha beta-BChl a transition energy heterogeneity, approximate to 600 cm(-1), which is much larger compared with other LH1 and LH2 complexes (80-200 cm(-1)). This large heterogeneity is induced by the inhomogeneous Coulomb (and possibly hydrogen-bonding) interactions exerted by Ba2+. The energy levels of the two LH1s were compared using exciton calculations in combination with Redfield theory. To simulate the FL splitting, an electronic transition containing two resonant bands was considered. This work shows how metal cations incorporated into the polypeptide modulate the electronic properties of BChl a aggregates.

AB - Two spectral forms of the core light-harvesting complex (LH1) of the purple bacterium Thermochromatium (Tch.) tepidum, the native Ca2+-binding and the Ba2+-substituted one, exhibit different fluorescence (FL) emission spectra at low temperature (T). While Ca-LH1 exhibits one emission band, an unusual splitting of the fluorescence is observed for Ba-LH1. These two sub-bands display the same spectral-width dependence according to T, but their intensity evolves differently with T. Based on the crystal structures, we propose that the FL splitting originates from a large alpha beta-BChl a transition energy heterogeneity, approximate to 600 cm(-1), which is much larger compared with other LH1 and LH2 complexes (80-200 cm(-1)). This large heterogeneity is induced by the inhomogeneous Coulomb (and possibly hydrogen-bonding) interactions exerted by Ba2+. The energy levels of the two LH1s were compared using exciton calculations in combination with Redfield theory. To simulate the FL splitting, an electronic transition containing two resonant bands was considered. This work shows how metal cations incorporated into the polypeptide modulate the electronic properties of BChl a aggregates.

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KW - alpha beta-BChl a heterogeneity

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