Anno2008
AutoriTumino G.; Casazza AP; Engelmann E.; Garlaschi F.M.; Zucchelli G.; Jennings R.C.
AbstractThe photosystem II kinetic model (diffusion or trap-limited) is still much debated. There is discussion about whether energy transfer from the core antenna (CP47 and CP43) to the reaction center complex (D1-D2-cyt b 559) is rate-limiting (transfer to trap-limited). This study investigates this problem in isolated core particles by exploiting the different optical properties of the core antenna and the reaction center complex near 680 nm, due to P680 and an isoenergetic pheophytin. This was used as a marker feature for the reaction center complex. If the transfer to the trap-limited model were correct, assuming excited-state thermalization, the specific reaction center fluorescence decay lifetime should be shorter near 680 nm, where there is reaction center complex specificity, than at the other emission wavelengths. Such a selective reaction center feature was not observed in fluorescence decay measurements. At the experimental resolution used here, we conclude that the trap-limited energy transfer to the reaction center could, at the most, be 20% limiting. Thus, the transfer to the trap-limited model is not supported. A kinetic, compartmental analysis was also performed on the data, taking into account a large number of separate measurements and the associated errors. Target analysis, considering these intermeasurement errors, yielded two minima which adequately describe the fluorescence lifetime data. The nonunique nature of the description is due to the fact that we have taken into consideration these intermeasurement errors. In our case, due to these errors, a correct kinetic model interpretation required additional experimental information.
RivistaBiochemistry (easton)
ISSN0006-2960
Impact factor
Volume47
Pagina inizio10449
Pagina fine10457
Autori IBFGiuseppe ZUCCHELLI, Robert Charles JENNINGS
Linee di Ricerca IBFMD.P01.005.001