The fluorescence selleck products decays were analyzed by software provided by Becker & Hickl (SPCImage). All measurements were performed at 22°C. The plants were dark-adapted at 20°C for 30 min before the measurements. Time-correlated single photon counting Time-correlated single photon counting (TCSPC) was used to perform time-resolved fluorescence measurements using a setup

described earlier (Borst et al. 2005). For the fitting procedure, the dynamic instrumental response of the experimental setup was recorded using the fast and single-exponential fluorescence decay (6 ps) of the reference compound pinacyanol in methanol (van Oort et al. 2008). Data analysis was performed using the computer program described earlier (Digris et al. 1999; Novikov et al. 1999). The fit quality was evaluated from χ2, and from the plots of the weighted residuals and the autocorrelation thereof (Visser et al. Defactinib manufacturer 2008). Typical values of χ2 were 1.0–1.1. For Chl a fluorescence measurements, the samples were excited at 470 nm, and the emission was collected using an interference filter at 688 nm with a bandwidth of 10 nm. The samples were sequentially thermostated at increasing

discrete temperatures, between 7 and 70°C, for 10 min at each temperature. The decay curves were analyzed by a four-exponential model; for each decay trace, the average lifetime (τave) was Selleckchem JQEZ5 calculated by the formula: $$ \tau_\textave = \sum\limits_i = 1^n \alpha_i \tau_i $$ τ being the fluorescence lifetime and α the pre-exponential factor proportional to the fractional population, with \( \sum\nolimits_i = 1^n \alpha_i = 1. \) For the calculation of τave, the minor contribution (typically about 1–2%) of a component

with a lifetime above 1 ns, originating from closed reaction centers, was not taken into account. Mannose-binding protein-associated serine protease The mean value of τave and its standard error presented in this article were determined from five different decay curves measured on different samples. Time-resolved fluorescence measurements of Merocyanine 540 For studying the lipid packing the lipophilic fluorescence probe, Merocyanine 540 (MC540, purchased from Sigma–Aldrich) was added, from a 1 mM ethanol stock solution (to a final concentration of 0.2 μM), to a suspension of thylakoid membranes (containing 20 μg Chl ml−1) and incubated for 30 min before the experiments. During this time, the sample was gently stirred and kept on ice in the dark. Longer incubation with MC540 did not result in increased incorporation of the probe (see Krumova et al. 2008a and references therein). For fluorescence lifetime measurements, the TCSPC set-up described in the previous section was used. The excitation wavelength was set to 570 nm, and the emission was collected between 610 and 630 nm using a Schott OG 610 nm (3 mm) cut-off filter and a Balzers K60 interference filter.