1. Excitonic states vs topological shape of membrane protein LH2
Protein structures in solution may differ from their crystal structures. X-ray crystal structure of light harvesting antenna complex LH2 from the photosynthetic bacteria Rhodopseudomonas acidophila reveals a perfect C9 symmetrical structure with a round topology. We investigated LH2 topological structure in solution by means of the Small Angle X-ray Scattering technique, our results show that the solution structure of LH2 from Rhodobacter spheriodes 2.4.1 and Rhodopseudomonas acidophila are elliptical.
Topological shape of LH2 in solution, embedded is the corresponding crystal structure.
We then further investigated the effect of nanoparticle-induced LH2 deformation on the lifetime of the LH2 excitonic state, and it is concluded that the B850 ring of the Bchlorophyll is reduced when LH2 disc is deformed following the curvature of the nanoparticle, which sheds light on that how the the excitonic states are modulated by the protein structural deformation.
Schematic diagram showing the assembly of LH2 onto the TiO2 nanoparticles and the corresponding kinetics.