title: Light-Induced Infrared Difference Spectroscopy in the Investigation of Light Harvesting Complexes.
abstract: Light-induced infrared difference spectroscopy (IR-DS) has been used, especially in the last decade, to investigate early photophysics, energy transfer and photoprotection mechanisms in isolated and membrane-bound light harvesting complexes (LHCs). The technique has the definite advantage to give information on how the pigments and the other constituents of the biological system (proteins, membranes, etc.) evolve during a given photoreaction. Different static and time-resolved approaches have been used. Compared to the application of IR-DS to photosynthetic Reaction Centers (RCs), however, IR-DS applied to LHCs is still in an almost pioneering age: very often sophisticated techniques (step-scan FTIR, ultrafast IR) or data analysis strategies (global analysis, target analysis, multivariate curve resolution) are needed. In addition, band assignment is usually more complicated than in RCs. The results obtained on the studied systems (chromatophores and RC-LHC supercomplexes from purple bacteria; Peridinin-Chlorophyll-a-Proteins from dinoflagellates; isolated LHCII from plants; thylakoids; Orange Carotenoid Protein from cyanobacteria) are summarized. A description of the different IR-DS techniques used is also provided, and the most stimulating perspectives are also described. Especially if used synergically with other biophysical techniques, light-induced IR-DS represents an important tool in the investigation of photophysical/photochemical reactions in LHCs and LHC-containing systems.
authors.affiliation: Laboratoire de Spectrochimie Infrarouge et Raman LASIR-UMR 8516, Université Lille 1, Bat C5, Cité Scientifique, 59655 Villeneuve d'Ascq, France. alberto.mezzetti@libero.it.|Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, CEA-Saclay, F-91191 Gif-sur-Yvette, France . alberto.mezzetti@libero.it.
authors.forename: Alberto
authors.initials: A
authors.lastname: Mezzetti
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis; D045342:Light-Harvesting Protein Complexes / Q000032:analysis*; D010940:Plant Proteins / Q000032:analysis; D013055:Spectrophotometry, Infrared / Q000379:methods*
chemical_list: D001426:Bacterial Proteins; D045342:Light-Harvesting Protein Complexes; D010940:Plant Proteins
keywords: LHCII; infrared difference spectroscopy; light-harvesting systems; orange carotenoid protein; peridinin; photoprotection; rapid-scan FTIR; step-scan FTIR; thylakoids