Abstract
Picosecond absorption and circular dichroism (CD) studies of photosynthetic reaction centers (RC) from Rhodabacter Sphaeroides are reported. The transient absorption spectra obtained are consistent with previous studies and provide definitive evidence for the formation of the two charge transfer intermediates: (BChl2)+BPhL-QA and (BChl2)+BPhLQA+ with rate constants whose half lives are <10 picosecond and $OM200 picoseconds, respectively. The transient circular dichroism spectra of these two charge separated intermediates are characterized by a nonconservative CD band centered at 800 nm with similar shape and intensity. This result clearly demonstrates that the negative CD band at 814 nm arises from the exciton coupling of the bacteriochlorophyll dimer. This transient CD cannot be due to excitonic interactions between the pigments in the reaction center and suggest that the monomer bacteriochlorophyll is either intrinsically chiral through distortions induced by the surrounding protein structure or obtains rotational strength from coupled oscillator interactions with surrounding aromatic residues in the protein.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
