The effects of detergents DDM and β-OG on the singlet excited state lifetime of the chlorophyll a in cytochrome b6f complex from spinach chloroplasts

The singlet excited state lifetime of the chlorophyll a (Chl a) in cytochrome b6f (Cyt b6o complex was reported to be shorter than that of free Chi a in methanol, but the value was different for Cyt b(6)f COMplexes from different sources (similar to 200 and similar to 600 ps are the two measured results). The present study demonstrated that the singlet excited state lifetime is associated with the detergents n-dodecyl-beta-D-maltoside (DDM) and n-octyl-beta-D-lucopyranoside (beta-OG), but has nothing to do with the different sources of Cyt b6f complexes. Compared with the Cyt b(6)f dissolved in beta-OG the Cyt b(6)f in DDM had a lower fluorescence yield, a lower photodegradation rate of Chl a, and a shorter lifetime of Chi a excited state. In short, the singlet excited state lifetime, similar to 200 ps, of the Chl a in Cyt b(6)fcomplex in DDM is closer to the true in vivo.