Interaction of linolenic acid with bound quinone molecules in Photosystem II. Time-resolved optical and electron spin resonance studies

John H. Golbeck, Joseph T. Warden

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Time-resolved spectroscopic techniques, including optical flash photolysis and electron spin resonance spectroscopy, have been utilized to monitor electron-transport activity in Photosystem II subchloroplast particles. These studies have indicated that in the presence of 100 μM linolenic acid (1) a high initial fluorescence yield (Fi) is observed upon steady-state illumination of the dark-adapted sample; (2) flash-induced absorption transients (t > 10 μs) in the region of 820 nm, attributed to P-680+, are first slowed, then abolished; and (3) electron spin resonance Signal IIs and Signal IIf (Z+) are not detectable. Upon reversal of linolenic acid inhibition by washing with bovine serum albumin, optical and electron spin resonance transients originating from the photooxidation of P-680 are restored. Similarly, the variable component of fluorescence is recovered with an accompanying restoration of Signal IIs and Signal IIf. The data indicate that linolenic acid affects two inhibition sites in Photosystem II: one located between pheophytin and QA on the reducing side, and the other between electron donor Z and P-680 on the oxidizing side. Since both sites are associated with bound quinone molecules, we suggest that linolenic acid interacts at the level of quinone binding proteins in Photosystem II.

Original languageEnglish (US)
Pages (from-to)263-271
Number of pages9
JournalBBA - Bioenergetics
Volume767
Issue number2
DOIs
StatePublished - Nov 26 1984

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alpha-Linolenic Acid
Photosystem II Protein Complex
Electron Spin Resonance Spectroscopy
Paramagnetic resonance
Molecules
Pheophytins
Fluorescence
Electron spin resonance spectroscopy
Photooxidation
Photolysis
Bovine Serum Albumin
Electron Transport
Lighting
Washing
Restoration
Carrier Proteins
Electrons
benzoquinone
P-680

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Cell Biology

Cite this

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abstract = "Time-resolved spectroscopic techniques, including optical flash photolysis and electron spin resonance spectroscopy, have been utilized to monitor electron-transport activity in Photosystem II subchloroplast particles. These studies have indicated that in the presence of 100 μM linolenic acid (1) a high initial fluorescence yield (Fi) is observed upon steady-state illumination of the dark-adapted sample; (2) flash-induced absorption transients (t > 10 μs) in the region of 820 nm, attributed to P-680+, are first slowed, then abolished; and (3) electron spin resonance Signal IIs and Signal IIf (Z+) are not detectable. Upon reversal of linolenic acid inhibition by washing with bovine serum albumin, optical and electron spin resonance transients originating from the photooxidation of P-680 are restored. Similarly, the variable component of fluorescence is recovered with an accompanying restoration of Signal IIs and Signal IIf. The data indicate that linolenic acid affects two inhibition sites in Photosystem II: one located between pheophytin and QA on the reducing side, and the other between electron donor Z and P-680 on the oxidizing side. Since both sites are associated with bound quinone molecules, we suggest that linolenic acid interacts at the level of quinone binding proteins in Photosystem II.",
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Interaction of linolenic acid with bound quinone molecules in Photosystem II. Time-resolved optical and electron spin resonance studies. / Golbeck, John H.; Warden, Joseph T.

In: BBA - Bioenergetics, Vol. 767, No. 2, 26.11.1984, p. 263-271.

Research output: Contribution to journalArticle

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AU - Golbeck, John H.

AU - Warden, Joseph T.

PY - 1984/11/26

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N2 - Time-resolved spectroscopic techniques, including optical flash photolysis and electron spin resonance spectroscopy, have been utilized to monitor electron-transport activity in Photosystem II subchloroplast particles. These studies have indicated that in the presence of 100 μM linolenic acid (1) a high initial fluorescence yield (Fi) is observed upon steady-state illumination of the dark-adapted sample; (2) flash-induced absorption transients (t > 10 μs) in the region of 820 nm, attributed to P-680+, are first slowed, then abolished; and (3) electron spin resonance Signal IIs and Signal IIf (Z+) are not detectable. Upon reversal of linolenic acid inhibition by washing with bovine serum albumin, optical and electron spin resonance transients originating from the photooxidation of P-680 are restored. Similarly, the variable component of fluorescence is recovered with an accompanying restoration of Signal IIs and Signal IIf. The data indicate that linolenic acid affects two inhibition sites in Photosystem II: one located between pheophytin and QA on the reducing side, and the other between electron donor Z and P-680 on the oxidizing side. Since both sites are associated with bound quinone molecules, we suggest that linolenic acid interacts at the level of quinone binding proteins in Photosystem II.

AB - Time-resolved spectroscopic techniques, including optical flash photolysis and electron spin resonance spectroscopy, have been utilized to monitor electron-transport activity in Photosystem II subchloroplast particles. These studies have indicated that in the presence of 100 μM linolenic acid (1) a high initial fluorescence yield (Fi) is observed upon steady-state illumination of the dark-adapted sample; (2) flash-induced absorption transients (t > 10 μs) in the region of 820 nm, attributed to P-680+, are first slowed, then abolished; and (3) electron spin resonance Signal IIs and Signal IIf (Z+) are not detectable. Upon reversal of linolenic acid inhibition by washing with bovine serum albumin, optical and electron spin resonance transients originating from the photooxidation of P-680 are restored. Similarly, the variable component of fluorescence is recovered with an accompanying restoration of Signal IIs and Signal IIf. The data indicate that linolenic acid affects two inhibition sites in Photosystem II: one located between pheophytin and QA on the reducing side, and the other between electron donor Z and P-680 on the oxidizing side. Since both sites are associated with bound quinone molecules, we suggest that linolenic acid interacts at the level of quinone binding proteins in Photosystem II.

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