Evidence that the intermediate electron acceptor, A2, in Photosystem I is a bound iron-sulfur protein

John H. Golbeck, B. R. Velthuys, B. Kok

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Absorption changes accompanying the formation of light-induced P-700+ were investigated in a highly enriched Photosystem I preparation where an intermediate electron acceptor preceding P-430 could be detected. In an enriched Photosystem I particle, light-induced reversible absorption changes observed at 700 nm in the presence of dithionite resembled those previously seen at 703 nm and 820 nm [9], thus indicating the presence of a backreaction between P-700+ and A- 2. After this same Photosystem I particle was treated to denature the bound iron-sulfur centers, the photochemical changes that could be attributed to P-700 A2 were completely lost. These results provide evidence that the intermediate electron acceptor, A2, is a bound iron-sulfur protein. Additional studies in the 400-500 nm region with Photosystem I particles prepared by sonication indicate that the spectrum of A2 is different from that of P-430.

Original languageEnglish (US)
Pages (from-to)226-230
Number of pages5
JournalBBA - Bioenergetics
Volume504
Issue number1
DOIs
StatePublished - Oct 11 1978

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Iron-Sulfur Proteins
Photosystem I Protein Complex
varespladib methyl
Electrons
Dithionite
Light
Sonication
Sulfur
Iron
chlorophyll P 700
P-430

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Medicine(all)

Cite this

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title = "Evidence that the intermediate electron acceptor, A2, in Photosystem I is a bound iron-sulfur protein",
abstract = "Absorption changes accompanying the formation of light-induced P-700+ were investigated in a highly enriched Photosystem I preparation where an intermediate electron acceptor preceding P-430 could be detected. In an enriched Photosystem I particle, light-induced reversible absorption changes observed at 700 nm in the presence of dithionite resembled those previously seen at 703 nm and 820 nm [9], thus indicating the presence of a backreaction between P-700+ and A- 2. After this same Photosystem I particle was treated to denature the bound iron-sulfur centers, the photochemical changes that could be attributed to P-700 A2 were completely lost. These results provide evidence that the intermediate electron acceptor, A2, is a bound iron-sulfur protein. Additional studies in the 400-500 nm region with Photosystem I particles prepared by sonication indicate that the spectrum of A2 is different from that of P-430.",
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Evidence that the intermediate electron acceptor, A2, in Photosystem I is a bound iron-sulfur protein. / Golbeck, John H.; Velthuys, B. R.; Kok, B.

In: BBA - Bioenergetics, Vol. 504, No. 1, 11.10.1978, p. 226-230.

Research output: Contribution to journalArticle

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