Conformation and orientation of chlorophyll-proteins in photosystem I by circular dichroism and polarized infrared spectroscopies

Eliane Nabedryk, Paule Biaudet, Sylvia Darr, Charles J. Arntzen, Jacques Breton

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

The protein conformation and orientation of Photosystem I (PS I) particles have been investigated by a combination of ultraviolet circular dichroism and polarized infrared spectroscopies. These PS I particles have been studied before and after reconstitution in phosphatidylcholine vesicles. The native state of the pigments of PS I was characterized by monitoring the low-temperature fluorescence emission spectra as well as the visible CD and linear dichroism spectra at room temperature. Computed analysis of the ultraviolet CD spectra of PS I complex indicates that the secondary structure of the protein is largely α-helical (52 ± 4%) with a very low amount of β-structure. Polarized infrared difference spectra of oriented PS I show a significant orientation of these α-helical segments with the α-helix axes tilted on the average at approx. 35° from the membrane normal.

Original languageEnglish (US)
Pages (from-to)640-647
Number of pages8
JournalBBA - Bioenergetics
Volume767
Issue number3
DOIs
StatePublished - Dec 18 1984

Keywords

  • (Pea chloroplast)
  • CD
  • Membrane reconstitution
  • Photosystem I
  • Polarized infrared spectroscopy
  • α-Helix orientation

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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