title: Versatile design of biohybrid light-harvesting architectures to tune location, density, and spectral coverage of attached synthetic chromophores for enhanced energy capture.
abstract: Biohybrid antennas built upon chromophore-polypeptide conjugates show promise for the design of efficient light-capturing modules for specific purposes. Three new designs, each of which employs analogs of the β-polypeptide from Rhodobacter sphaeroides, have been investigated. In the first design, amino acids at seven different positions on the polypeptide were individually substituted with cysteine, to which a synthetic chromophore (bacteriochlorin or Oregon Green) was covalently attached. The polypeptide positions are at -2, -6, -10, -14, -17, -21, and -34 relative to the 0-position of the histidine that coordinates bacteriochlorophyll a (BChl a). All chromophore-polypeptides readily formed LH1-type complexes upon combination with the α-polypeptide and BChl a. Efficient energy transfer occurs from the attached chromophore to the circular array of 875 nm absorbing BChl a molecules (denoted B875). In the second design, use of two attachment sites (positions -10 and -21) on the polypeptide affords (1) double the density of chromophores per polypeptide and (2) a highly efficient energy-transfer relay from the chromophore at -21 to that at -10 and on to B875. In the third design, three spectrally distinct bacteriochlorin-polypeptides were prepared (each attached to cysteine at the -14 position) and combined in an ~1:1:1 mixture to form a heterogeneous mixture of LH1-type complexes with increased solar coverage and nearly quantitative energy transfer from each bacteriochlorin to B875. Collectively, the results illustrate the great latitude of the biohybrid approach for the design of diverse light-harvesting systems.
authors.affiliation: Department of Chemistry, Washington University, St. Louis, MO, 63130-4889, USA.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Harris
authors.forename: Jianbing
authors.initials: J
authors.lastname: Jiang
authors.forename: Dariusz M
authors.initials: DM
authors.lastname: Niedzwiedzki
authors.forename: Jieying
authors.initials: J
authors.lastname: Jiao
authors.forename: Masahiko
authors.initials: M
authors.lastname: Taniguchi
authors.forename: Christine
authors.initials: C
authors.lastname: Kirmaier
authors.forename: Paul A
authors.initials: PA
authors.lastname: Loach
authors.forename: David F
authors.initials: DF
authors.lastname: Bocian
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Lindsey
authors.forename: Dewey
authors.initials: D
authors.lastname: Holten
authors.forename: Pamela S
authors.initials: PS
authors.lastname: Parkes-Loach
mesh_terms: D001429:Bacteriochlorophylls / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017433:Protein Structure, Secondary; D012242:Rhodobacter sphaeroides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D001429:Bacteriochlorophylls; D045342:Light-Harvesting Protein Complexes