Photosystem I

I. Grotjohann, Petra Fromme

Research output: Chapter in Book/Report/Conference proceedingChapter

2 Scopus citations


Photosystem I (PSI) is one of the key players in the process of oxygenic photosynthesis. This large membrane protein complex utilizes light energy to transfer electrons from the lumenal electron carriers plastocyanin or cytochrome c6 across the photosynthetic membrane to the stromal/cytosolic electron carriers ferredoxin or flavodoxin. The resulting proton gradient is used for adenosine triphosphate (ATP) production by the ATP synthase, while the electrons end up in carbon fixation. With a molecular weight of 1 million Da, trimeric cyanobacterial PSI is one of the largest membrane protein complexes with known structure. About one-third of its molecular weight comes from cofactors, mainly chlorophylls, and also carotenoids, phylloqinones, and iron-sulfur clusters.

Original languageEnglish (US)
Title of host publicationEncyclopedia of Biological Chemistry
Subtitle of host publicationSecond Edition
PublisherElsevier Inc.
Number of pages5
ISBN (Electronic)9780123786319
ISBN (Print)9780123786302
StatePublished - Feb 15 2013


  • Charge separation
  • Chlorophyll
  • Cytochrom c
  • Electrochemical gradient
  • Electron transfer chain
  • Excitation energy transfer
  • Ferredoxin
  • Flavodoxin
  • Iron-sulfur cluster
  • Oxygenic photosynthesis
  • Photosynthesis
  • Photosystem
  • Photosystem I
  • Phylloquinone
  • Plastocyanin
  • PSI

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology


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