title: Near-infrared resonance Raman spectra of Chloroflexus aurantiacus photosynthetic reaction centers.
abstract: Resonance Raman spectra of the photosynthetic reaction center isolated from the green bacterium Chloroflexus aurantiacus have been obtained with excitation in the near-infrared absorption bands of the special pair (P) and the accessory bacteriochlorophyll (B) using shifted-excitation Raman difference spectroscopy (SERDS). These spectra are compared with the previously reported Raman spectra of P and B in reaction centers from the purple bacterium Rhodobacter sphaeroides. The spectra of P and B from the two species are nearly identical. Common and distinctive attributes of these spectra include enhanced low-frequency (30-200 cm-1) modes in P and the absence of strong Raman activity in modes higher than 1200 cm-1 in both P and B. Also, the absolute scattering cross sections with excitation in the P band are unusually weak in both reaction centers, indicating that their excited states are rapidly vibronically dephased. The striking similarities between the P and B spectra in reaction centers from two very different bacterial species suggest that the common nuclear and electronic dynamics identified here are characteristic of photosynthetic reaction centers.
authors.affiliation: Department of Chemistry, University of California, Berkeley 94720, USA.
authors.forename: N J
authors.initials: NJ
authors.lastname: Cherepy
authors.forename: A R
authors.initials: AR
authors.lastname: Holzwarth
authors.forename: R A
authors.initials: RA
authors.lastname: Mathies
mesh_terms: D001419:Bacteria / Q000737:chemistry*; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D012242:Rhodobacter sphaeroides / Q000737:chemistry; D013059:Spectrum Analysis, Raman / Q000379:methods
chemical_list: D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins