Quantitation of labile sulfide content and P700 photochemistry in spinach photosystem I particles

John H. Golbeck, Stephen Lien, Anthony San Pietro

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Treatment of spinach photosystem I particles with 2 or 4 M urea containing 5 mM ferricyanide produces a time-dependent conversion of labile sulfide to zero-valence sulfur in the membrane-bound iron-sulfur proteins. The integrity of the primary electron donor, P700, remains intact when measured as a chemical oxidized-minus-reduced difference spectrum. The effect on the light-induced oxidation of P700 is complex; the extent of the normally-fast P700 photooxidation correlates directly with the amount of labile sulfide remaining in the particle but a slow phase of photooxidation only becomes evident in increasingly depleted particles and shows no relationship with the amount of remaining labile sulfide. The data is taken as evidence for the participation of an iron-sulfur protein in the primary photochemistry of photosystem I in green plants.

Original languageEnglish (US)
Pages (from-to)452-458
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number2
StatePublished - Jul 26 1976

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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