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Flash‐photolysis studies of the electron transfer from genetically modified spinach plastocyanin to photosystem I
Author(s) -
Nordling Margareta,
Sigfridsson Kalle,
Young Simon,
Lundberg Lennart G.,
Hansson Örjan
Publication year - 1991
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(91)81313-w
Subject(s) - plastocyanin , electron transfer , photosystem ii , flash photolysis , photochemistry , spinach , chemistry , photosystem i , p700 , flash (photography) , biophysics , photosynthesis , biology , biochemistry , physics , kinetics , optics , quantum mechanics , reaction rate constant
Plastocyanin (Pc) has been modified by site‐directed mutagenesis at two separate electron‐transfer (ET) sites: Leu‐12‐Glu at a hydrophobic patch, and Tyr‐83‐His at an acidic patch. The reduction potential at pH 7.5 is decreased by 26 mV in Pc(Leu‐12‐Glu) and increased by 35 mV in Pc(Tyr‐83‐His). The latter mutant shows a 2‐fold slower intracomplex ET to photosystem I (PSI) as expected from the decreased driving force. The affinity for PSI is unaffected for this mutant but is drastically decreased for Pc(Leu‐12‐Glu). It is concluded that the hydrophobic patch is more important for the ET to PSI.