title: Photo-induced proton gradients and ATP biosynthesis produced by vesicles encapsulated in a silica matrix.
abstract: Sol-gel immobilization of soluble proteins has proven to be a viable method for stabilizing a wide variety of proteins in transparent inorganic matrices. The encapsulation of membrane-bound proteins has received much less attention, although work in this area suggests potential opportunities in microarray technology and high-throughput drug screening. The present paper describes a liposome/sol-gel architecture in which the liposome provides membrane structure and protein orientation to two transmembrane proteins, bacteriorhodopsin (bR) and F(0)F(1)-ATP synthase; the sol-gel encapsulation converts the liposomal solution into a robust material without compromising the intrinsic activity of the incorporated proteins. Here we report on two different proteoliposome-doped gels (proteogels) whose properties are determined by the transmembrane proteins. Proteogels containing bR proteoliposomes exhibit a stable proton gradient when irradiated with visible light, whereas proteogels containing proteoliposomes with both bR and F(0)F(1)-ATP synthase couple the photo-induced proton gradient to the production of ATP. These results demonstrate that materials based on the liposome/sol-gel architecture are able to harness the properties of transmembrane proteins and enable a variety of applications, from power generation and energy storage to the powering of molecular motors, and represent a new technology for performing complex chemical synthesis in a solid-state matrix.
authors.affiliation: Department of Materials Science and Engineering, University of California, Los Angeles, California 90095, USA.
authors.forename: Tzy-Jiun M
authors.initials: TJ
authors.lastname: Luo
authors.forename: Ricky
authors.initials: R
authors.lastname: Soong
authors.forename: Esther
authors.initials: E
authors.lastname: Lan
authors.forename: Bruce
authors.initials: B
authors.lastname: Dunn
authors.forename: Carlo
authors.initials: C
authors.lastname: Montemagno
mesh_terms: D000255:Adenosine Triphosphate / Q000138:chemical synthesis*; D001426:Bacterial Proteins / Q000737:chemistry*; D025243:Bacterial Proton-Translocating ATPases; D001436:Bacteriorhodopsins / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry*; D011522:Protons; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D008081:Liposomes; D011522:Protons; D001436:Bacteriorhodopsins; D012822:Silicon Dioxide; D000255:Adenosine Triphosphate; D025243:Bacterial Proton-Translocating ATPases