Inhibition of Photosystem II of Spinach by the Respiration Inhibitors Piericidin A and Thenoyltrifluoroacetone

Abstract

The effects of several respiration inhibitors on photosystem II (PS II) were investigated. Among the agents tested, piericidin A and thenoyltrifluoroacetone (TTFA) inhibited the photosynthetic electron transport of spinach as measured from chlorophyll (Chl) fluorescence parameters (Fm′−F)/Fm′ and Fv/Fm. Using specific donors and acceptors of electrons, we identified the sites of inhibition in and around the PS II complex; the site of inhibition by TTFA was between Q_A, primary quinone acceptor in PS II, and Q_B, secondary quinone acceptor, in the acceptor side of P680, the reaction center Chl of PS II, while inhibition by piericidin A of the acceptor side was downstream of Q_B, out of the PS II complex. Both agents also inhibited the donor side of P680, probably between tyrosine-161 of the reaction center protein of PS II and P680.

• chlorophyll fluorescence
• photosystem II inhibitors
• piericidin A
• spinach
• thenoyltrifluoroacetone