Open AccessA third site of porton translocation in green plant photosynthetic electron transport
Author(s) -
B.R. Velthuys
Publication year - 1978
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.75.12.6031
Subject(s) - plastoquinone , ferricyanide , electron transport chain , chemistry , electron transfer , photosystem ii , proton transport , chloroplast , proton , photochemistry , photosynthesis , thylakoid , inorganic chemistry , biochemistry , membrane , physics , quantum mechanics , gene
Prereduction of the intersystem pool in isolated spinach chloroplasts leads to the appearance of a slow phase in the field-indicating 515-nm change induced by a flash. Measurements with the pH-indicator dye cresol red show that a proton uptake is associated with this slow 515-nm change. When water is the electron donor to photosystem II, electron transfer to ferricyanide is associated with the uptake of more than one proton per electron. Tetraphenylboron upon oxidation by system II releases a proton directly into the medium; yet, flash-induced electron transport from tetraphenylboron to ferricyanide is accompanied by a net uptake of protons from the medium. The above four results demonstrate the existence of two proton translocation sites in the chain between the two photoacts; the first two observations locate the new site at the oxidizing side of the plastoquinone pool.