Figure 5.

Schematic representation of the pressure cell (A) specially designed for TR-MIMS measurements of light-induced ¹⁸O₂ evolution of PSII under high ¹⁶O₂/N₂ pressures (up to 20 bars). (B) MIMS signals in panel (B); Left: ¹⁸O₂ production of PSII core complexes from Synechocystis sp. PCC 6803 induced by a series of 200 saturating Xenon flashes (given at 2 Hz; indicated by arrow) at 21.7 bars O₂, or 20 bars N₂. Other conditions: 30% H¹⁸₂O enrichment; [Chl] = 50 μM; 250 μM DCBQ, pH 6.7, 20°C. Right: Flash-induced ¹⁸O₂ evolution patterns of PSII membrane fragments from spinach induced by a series of saturating laser flashes (separated by dark times of 25 s) at 20.4 bars O₂, or 20.2 bars N₂. Other conditions: as above, but with 40% H¹⁸₂O. Adapted from Shevela et al. (2011a).