PEG effects on excitonic properties of LH2 from Rhodobacter sphaeroides 2.4.1 in different environments

The effects of Polyethylene glycol (PEG) on B800 and B850 excitonic properties of the Light-Harvesting complex 2 (LH2) from Rhodobacter (Rba.) sphaeroides 2.4.1 in micellar solutions of detergents and phospholipid bilayers were investigated by a series of spectroscopies. Compared to the micellar solution, in the lipid bilayer, the lateral force applied on LH2 changed the excitonic structure of B850 and weakened the excitonic interaction between B800 molecules. In micelles, PEG addition causes LH2 aggregation, resulting in the enhancement of B850 excitonic coupling inter-complexes and conformational change of the bound carotenoid (Car). In liposomes, PEG addition causes similar to 37 % fluorescence quenching of B850 excitons in the embedded LH2s by changing the surrounding hydration state.

Automated summary

The effects of Polyethylene glycol (PEG) on B800 and B850 excitonic properties of the Light-Harvesting complex 2 (LH2) from Rhodobacter sphaeroides 2.4.1 were investigated. PEG addition in micellar solutions caused LH2 aggregation and enhanced B850 excitonic coupling between inter-complexes, as well as conformational changes of the bound carotenoid (Car). In liposomes, PEG addition resulted in approximately 37% fluorescence quenching of B850 excitons in the embedded LH2s by altering the surrounding hydration state.