Energy transfer within pc trimers of mastigocladus laminosus studied bypicosecond time-resolved transient absorption Spectroscopy

Abstract

The transient absorption recovery induced in phycocyanin trimers by picosecond pulses of variable wavelength (570–620 nm) has been recorded and analyzed by applying a least-squares multi-exponential fit procedure.The results suggest that in native PC trimers the chromophores exhibit a microheterogeneity with the effect that the derived apparent lifetimes are functions of excitation and probing wavelength.It is suggested that, due to strong excitonic coupling between a-84 and ß-84 chromophores, the lifetime of the terminal acceptor state is reduced to about 900 ps; the apparent energy transfer time from chromophore ß-155 to a-84 and ß-84 chromophores varies between 20–50 ps depending on the actual chromophore-protein arrangement (microheterogeneity). © 1988, Walter de Gruyter. All rights reserved.