title: Insertion of bacteriorhodopsin into polymerized diacetylenic phosphatidylcholine bilayers.
abstract: We have developed a method to incorporate the membrane protein bacteriorhodopsin into polymerized bilayers composed of a diacetylenic phosphatidylcholine, 1,2-bis(tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine (DC8,9PC) and a non-polymerizable phospholipid, dinonanoylphosphatidylcholine (DNPC). The extent of DC8,9PC polymerization in the bilayer was significantly improved when 2:1 mole ratio DNPC-DC8,9PC was used. Octyl glucopyranoside-solubilized bacteriorhodopsin was inserted into the polymerized DNPC-DC8,9PC bilayers by overnight incubation at 4 degrees C followed by dialysis to remove the detergent. The protein was inserted into the membranes after photo-polymerization to avoid inactivation of the protein due to the UV irradiation. The insertion of bacteriorhodopsin into the polymerized DNPC-DC8,9PC membranes was confirmed by density gradient centrifugation, UV/visible spectroscopy, and freeze fracture electron microscopy. The polymerized DNPC-DC8,9PC membranes containing bacteriorhodopsin were about 10% protein by weight. These results suggest that mixed lipid systems such as the DNPC-DC8,9PC can be used to improve both the extent of polymerization and the efficiency of membrane protein incorporation in the polymerized bilayer.
authors.affiliation: Center for Bio/molecular Science and Engineering, Naval Research Laboratory, Washington, DC.
authors.forename: P L
authors.initials: PL
authors.lastname: Ahl
authors.forename: R
authors.initials: R
authors.lastname: Price
authors.forename: J
authors.initials: J
authors.lastname: Smuda
authors.forename: B P
authors.initials: BP
authors.lastname: Gaber
authors.forename: A
authors.initials: A
authors.lastname: Singh
mesh_terms: D001436:Bacteriorhodopsins; D005614:Freeze Fracturing; D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D011108:Polymers; D013056:Spectrophotometry, Ultraviolet
chemical_list: D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D011108:Polymers; D001436:Bacteriorhodopsins