The experimental traces in general represent the averages of three samples each illuminated once. The simulation
and fitting of the experimental polyphasic fluorescence induction curve with its algorithmic representation F FIA(t) was done with dedicated optimization routines. The fit parameters (rate constants, heterogeneity, fraction, etc.) of the simulation curve F FIA(t) were estimated after application of dedicated routines provided by appropriate software (Mathcad 13, MathSoft, Inc. Cambridge, MA, USA) which calculates the parameter values (vector) for which the least mean square function is minimal, where NN is the number of data points (in most experiments NN ≥50). Reduction of data points was in some cases purposely applied selleck chemical for F FIA(t) curves to facilitate better comparison with the experimental curve F exp(t). Analysis with fluorescence induction algorithm It has been shown (Vredenberg and Prásil 2009; Vredenberg 2011) that
the variable fluorescence during the OJ phase in the 0.01–1 ms time range is nearly exclusively, if not completely due to the release of primary photochemical quenching q PP and is represented by F PP(t) with $$ F^\textPP selleck chemicals (t) = 1 + nF_\textv \cdot q^\textdsq (t) \cdot [(1 - \beta ) \cdot \frack_\textL k_\textL + k_\textAB + \beta \cdot (1 + (1 - e^ - \phi k_\textL t ) \cdot e^ - k_2\textAB t )] $$ (1)in which nF v (=F m STF −F o)/F o) is the normalized variable fluorescence, \( q^\textdsq (t) = 1 – \texte^ – k_\textL t , \) β is the fraction of QB-nonreducing Methamphetamine RCs, Φ(0 ≤ Φ < 1)is an efficiency factor for energy trapping in semi-closed QB-nonreducing RCs, and k L, k AB, and k 2AB are the rate constants of light excitation and of oxidation of the single- and double-reduced primary quinone acceptor QA of PSII, respectively. Similarly it was shown that the variable fluorescence during the JI phase in the 1–30 ms time range is nearly exclusive due to the release of photoelectrochemical quenching q PE and is in approximation represented by F PE(t) with $$ F^\textPE (t) = 1 + nF_\textv \cdot
\ [1 - f^\textPPsc (t)] \cdot [1 - e^ - k_\textqbf \cdot t ] \cdot \frack_\textqbf k_\textqbf + k_\textHthyl + 1\ \cdot [1 - e^ - k_\textqbf \cdot t ] \cdot \frack_\textqbf k_\textqbf + k_\textHthyl $$ (2)in which f PPsc(t) is the fraction of semi-closed RCs containing QA − (see for definitions and equations Vredenberg 2011), k qbf is the rate constant attributed to that of the change in pH at the QA − QB redox side of PSII (related to the actual rate constant of proton pumping by the trans-thylakoid proton pump), and k Hthyl the actual passive trans-thylakoid proton leak (selleck screening library conductance). For the experiments presented in this article changes in k qbf and k Hthyl will be of prime importance to be considered.