Investigation of the dynamics of bacteriorhodopsin

Bacteriorhodopsin (bR) converted to the blue form by deionization has been reconstituted to the active purple membrane by addition of⁵⁷Fe ions. Mössbauer spectra measured in a wide temperature range reveal Fe³⁺ binding places with oxygen atoms in the neighbourhood. No evidence for a well defined functional binding place of the iron has been found. On a timescale faster 100 ns the purple membrane shows increasing flexibility above 200 K. In order to analyse the influence of the lipids, a bacteriorhodopsin sample where the lipid content has been increased artificially by the incorporation of DMPC as well as a sample consisting of lipid bilayer have been investigated.