UV/VIS Spectroscopy of Membrane Proteins Encapsulated into Artificial Bilayer Lipid Membranes

An artificial bilayer lipid membrane system was employed, featuring the oriented encapsulation of membrane proteins in a functionally active form. Nickel-nitrilo-tri-acetic acid-functionalized silica nanoparticles of a diameter of around 25 nm were used to attach the proteins via a genetically engineered histidine-tag in a uniform orientation. Subsequently the proteins were reconstituted within a phospholipid bilayer, formed around the particles by in-situ dialysis to form so-called proteo-lipobeads (PLBs). With a final size of about 50 nm, the PLBs could be employed for UV/VIS spectroscopy studies, particularly of multi-redox center proteins, since effects of light scattering are negligible. Andor Technology imaging instruments were employed including the Shamrock SR-303i and Newton CCD and EMCCD Cameras.