Evaluation of photosynthetic activities in thylakoid membranes by means of Fourier transform infrared spectroscopy

Ryo Nagao, Sho Kitazaki, Takumi Noguchi

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Light-induced Fourier transformed infrared (FTIR) difference spectroscopy is a powerful method to study the structures and reactions of redox cofactors involved in the photosynthetic electron transport chain. So far, most of the FTIR studies of the reactions of oxygenic photosynthesis have been performed using isolated photosystem I (PSI) and photosystem II (PSII) preparations, which, however, could be modified during isolation procedures. In this study, we developed a methodology to evaluate the photosynthetic activities of thylakoids using FTIR spectroscopy. FTIR difference spectra upon successive flashes using thylakoids from spinach exhibited signals typical of the S-state cycle at the Mn4CaO5 cluster and QB reactions in PSII with period-four and -two oscillations, respectively. Similar measurement in the presence of an artificial quinone as an exogenous electron acceptor showed features specific to the S-state cycle. Simulations of the oscillation patterns provided the quantum efficiencies of the S-state cycle and electron transfer in PSII. Moreover, FTIR measurement under continuous illumination on thylakoids in the presence of DCMU showed signals due to QA reduction and P700 oxidation simultaneously. From the relative amplitudes of marker bands of QA and P700+, the molar ratio of photoactive PSII and PSI centers in thylakoids was estimated. FTIR analyses of the photo-reactions in thylakoids, which are more intact than isolated photosystems, will be useful in investigations of the photosynthetic mechanism especially by genetic modification of photosystem proteins.

Original languageEnglish
Pages (from-to)129-136
Number of pages8
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume1859
Issue number2
DOIs
Publication statusPublished - Feb 2018

Keywords

  • Electron transfer
  • FTIR
  • Oxygen evolution
  • Photosystem
  • Thylakoid
  • Water oxidation

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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