title: In vitro self-assembly of the light harvesting pigment-protein LH2 revealed by ultrafast spectroscopy and electron microscopy.
abstract: Controlled ensemble formation of protein-surfactant systems provides a fundamental concept for the realization of nanoscale devices with self-organizing capability. In this context, spectroscopic monitoring of pigment-containing proteins yields detailed structural information. Here we have studied the association behavior of the bacterial light-harvesting protein LH2 from Rhodobacter spheroides in an n,n-dimethyldodecylamine-n-oxide/water environment. Time-resolved studies of the excitation annihilation yielded information about aggregate sizes and packing of the protein complexes therein. The results are compared to transmission electron microscopy images of instantaneously frozen samples. Our data indicate the manifestation of different phases, which are discussed with respect to the thermodynamic equilibrium in ternary protein-surfactant-water systems. Accordingly, by varying the concentration the formation of different types of aggregates can be controlled. Conditions for the appearance of isolated LH2 complexes are defined.
authors.affiliation: Chemical Physics, Lund University, Lund, Sweden.
authors.forename: Axel
authors.initials: A
authors.lastname: Schubert
authors.forename: Anna
authors.initials: A
authors.lastname: Stenstam
authors.forename: Wichard J D
authors.initials: WJ
authors.lastname: Beenken
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Herek
authors.forename: Richard
authors.initials: R
authors.lastname: Cogdell
authors.forename: Tõnu
authors.initials: T
authors.lastname: Pullerits
authors.forename: Villy
authors.initials: V
authors.lastname: Sundström
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D003198:Computer Simulation; D004123:Dimethylamines / Q000737:chemistry; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry*; D008854:Microscopy, Electron; D010860:Pigments, Biological / Q000737:chemistry*; D012242:Rhodobacter sphaeroides / Q000737:chemistry; D013057:Spectrum Analysis; D014867:Water / Q000737:chemistry
chemical_list: C081521:B800-850 light-harvesting complex, bacteria; D001426:Bacterial Proteins; D004123:Dimethylamines; D045342:Light-Harvesting Protein Complexes; D010860:Pigments, Biological; D014867:Water; C014518:dodecyldimethylamine oxide