caa a22 4500 445890150 CHVBK 20180317145613.0 cr unu---uuuuu 170323e20110901xx s 000 0 eng 10.1007/s11120-011-9666-9 doi (NATIONALLICENCE)springer-10.1007/s11120-011-9666-9 Effects of the measuring light on the photochemistry of the bacterial photosynthetic reaction center from Rhodobacter sphaeroides [Elektronische Daten] [Ivan Husu, Mauro Giustini, Giuseppe Colafemmina, Gerardo Palazzo, Antonia Mallardi] The bacterial reaction center (RC) has become a reference model in the study of the diverse interactions of quinones with electron transfer complexes. In these studies, the RC functionality was probed through flash-induced absorption changes where the state of the primary donor is probed by means of a continuous measuring beam and the electron transfer is triggered by a short intense light pulse. The single-beam set-up implies the use as reference of the transmittance measured before the light pulse. Implicit in the analysis of these data is the assumption that the measuring beam does not elicit the protein photochemistry. At variance, measuring beam is actinic in nature at almost all the suitable wavelengths. In this contribution, the analytical modelling of the time evolution of neutral and charge-separated RCs has been performed. The ability of measuring light to elicit RC photochemistry induces a first order growth of the charge-separated state up to a steady state that depends on the light intensity and on the occupation of the secondary quinone (QB) site. Then the laser pulse pumps all the RCs in the charge-separated state. The following charge recombination is still affected by the measuring beam. Actually, the kinetics of charge recombination measured in RC preparation with the QB site partially occupied are two-exponential. The rate constant of both fast and slow phases depends linearly on the intensity of the measuring beam while their relative weights depend not only on the fractions of RC with the QB site occupied but also on the measuring light intensity itself. Springer Science+Business Media B.V., 2011 Rhodobacter sphaeroides nationallicence Reaction center nationallicence Electron transfer nationallicence Light intensity nationallicence Husu Ivan Dipartimento di Chimica, Università "La Sapienza”, 00185, Rome, Italy aut Giustini Mauro Dipartimento di Chimica, Università "La Sapienza”, 00185, Rome, Italy aut Colafemmina Giuseppe Dipartimento di Chimica, Università di Bari, via Orabona 4, 70126, Bari, Italy aut Palazzo Gerardo Dipartimento di Chimica, Università di Bari, via Orabona 4, 70126, Bari, Italy aut Mallardi Antonia CNR-IPCF, Istituto per i Processi Chimico-Fisici, 70126, Bari, Italy aut Photosynthesis Research Springer Netherlands 108/2-3(2011-09-01), 133-142 0166-8595 108:2-3<133 2011 108 11120 https://doi.org/10.1007/s11120-011-9666-9 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11120-011-9666-9 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Husu Ivan Dipartimento di Chimica, Università "La Sapienza”, 00185, Rome, Italy aut NATIONALLICENCE 700 1- Giustini Mauro Dipartimento di Chimica, Università "La Sapienza”, 00185, Rome, Italy aut NATIONALLICENCE 700 1- Colafemmina Giuseppe Dipartimento di Chimica, Università di Bari, via Orabona 4, 70126, Bari, Italy aut NATIONALLICENCE 700 1- Palazzo Gerardo Dipartimento di Chimica, Università di Bari, via Orabona 4, 70126, Bari, Italy aut NATIONALLICENCE 700 1- Mallardi Antonia CNR-IPCF, Istituto per i Processi Chimico-Fisici, 70126, Bari, Italy aut NATIONALLICENCE 773 0- Photosynthesis Research Springer Netherlands 108/2-3(2011-09-01), 133-142 0166-8595 108:2-3<133 2011 108 11120 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer