Femtosecond spectroscopy of electron transfer in the reaction center of the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26: Direct electron transfer from the dimeric bacteriochlorophyll primary donor to the bacteriopheophytin acceptor with a time constant of 2.8 ± 0.2 psec

AUTOR(ES)

Martin, J.-L.

RESUMO

The primary light-induced charge separation in reaction centers from Rhodopseudomonas sphaeroides R-26 has been investigated after excitation with laser pulses of 150 fsec duration within the longwave absorption band of the primary donor at 850 nm. An excited state of the primary donor, characterized by a broad absorption spectrum extending over the whole spectral range investigated (545-1240 nm), appeared within 100 fsec and gave rise to stimulated emission in the 870- to 1000-nm region with a 2.8-psec lifetime. The photooxidation of the primary donor, as measured at 1240 nm, and the photoreduction of the bacteriopheophytin acceptor, monitored at 545 nm and 675 nm, have been found to proceed simultaneously with a time constant of 2.8 ± 0.2 psec. Kinetics of absorbance changes at other probe wavelengths gave no indication that an accessory bacteriochlorophyll is involved as a transient electron acceptor.

Documentos Relacionados

• Femtosecond spectroscopy of excitation energy transfer and initial charge separation in the reaction center of the photosynthetic bacterium Rhodopseudomonas viridis
• Structure of the reaction center from Rhodobacter sphaeroides R-26 and 2.4.1: protein-cofactor (bacteriochlorophyll, bacteriopheophytin, and carotenoid) interactions.
• In vivo intermembrane transfer of phospholipids in the photosynthetic bacterium Rhodopseudomonas sphaeroides.
• Structure of the reaction center from Rhodobacter sphaeroides R-26: the cofactors.
• Plasmid rearrangements in the photosynthetic bacterium Rhodopseudomonas sphaeroides.