Rapid-scan FTIR difference spectroscopy applied to ubiquinone reduction in photosynthetic reaction centers: Role of redox mediators
Issue title: From Molecule to Tissue: XIII European Conference on the Spectroscopy of Biological Molecules, Palermo, Italy, August 28–September 2, 2009, Part 1 of 2
Affiliations: Service de Bioénergétique, Biologie Structurale et Mécanismes, IBiTec-S, CEA-Saclay, Gif-sur-Yvette, France | LASIR UMR 8516, Université Lille 1, Villeneuve d'Ascq, France
Note: [] Address for correspondence: Alberto Mezzetti, Service de Bioénergétique, Biologie Structurale et Mécanismes, IBiTec-S, Bât 532, CEA-Saclay, 91191 Gif-sur-Yvette cedex, France. Tel.: +33 1 69082633; Fax: +33 1 69088717. E-mail: [email protected].
Abstract: Rapid-scan FTIR difference spectroscopy was used to investigate light-induced reduction of the ubiquinone QB, and the oxidation kinetics of QB− and QH2 by external mediators in isolated reaction centers (RCs) from R. sphaeroides. As redox mediators, a Ferrocyanide/N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) mixture and an Ascorbate/2,3,5,6-tetramethyl-p-phenylenediamine (DAD) mixture are compared. Results show that TMPDred rapidly reduces the photoproduced P870+ primary donor. The process is fast enough to record rapid-scan FTIR spectra devoid of P870+ bands down to 260 K. Results show also that TMPDox oxidises both QB− and QH2 faster than DADox. In particular, QB− is oxidised faster than QH2 at all temperatures studied. Results are discussed in the framework of time-resolved infrared studies on R. sphaeroides RCs, showing advantages/drawbacks of the proposed experimental approach.
Keywords: Reaction center, redox mediators, TMPD, DAD, rapid-scan FTIR, ubiquinone
DOI: 10.3233/SPE-2010-0435
Journal: Spectroscopy, vol. 24, no. 1-2, pp. 79-87, 2010
