Interaction of photosynthetic pigments with various organic solvents. Magnetic circular dichroism approach and application to chlorosomes

Mitsuo Umetsu, Zheng Yu Wang, Masayuki Kobayashi, Tsunenori Nozawa

Research output: Contribution to journalArticlepeer-review

63 Citations (Scopus)

Abstract

Magnetic circular dichroism (MCD) and absorption spectra have been measured on three intact photosynthetic pigments with the chlorin ring as macrocycle: chlorophyll a, bacteriochlorophyll c and d, in various hydrophilic organic solvents. The MCD intensity of a Q(y)(0-0) transition for the Mg chlorin derivative was sensitive to the coordination state of the central Mg atom by the solvent molecules. The coordination number has been characterized in terms of the relationship between the ratio of Q(y)(0-0) MCD intensity to its dipole strength (B/D) and the difference in energies of Q(x)(0-0) and Q(y)(0-0) transitions. This relationship depends not only on the coordination number of the magnesium (Mg) atom but also on the coordination interaction of the solvent molecules to the Mg atom, and can clarify the spectroscopic change of chlorosomes by alcohol treatment. We propose that the correlation between the MCD intensity of Q(y)(0-0) transition and the energy difference can be used as a new measure for determining the coordination number of the Mg atom and for estimating the interaction strength of the Mg atom with solvent molecules. Copyright (C) 1999 Elsevier Science B.V.

Original languageEnglish
Pages (from-to)19-31
Number of pages13
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume1410
Issue number1
DOIs
Publication statusPublished - 1999 Jan 27

Keywords

  • Alcohol treatment
  • Bacteriochlorophyll c
  • Chlorosome
  • Coordination state
  • Magnetic circular dichroism

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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