title: Flavodoxin relaxes in microseconds upon excitation of the flavin chromophore: detection of a UV-visible silent intermediate by laser photocalorimetry.
abstract: A small contraction concomitant with the relaxation of the protein in ca. 3 mus is observed upon ns-laser excitation at 455 nm of the Cys69Ala (C69A) mutant of flavodoxin II from Azotobacter vinelandii. This constitutes another example of detection of a UV-vis silent transient species through a photocalorimetric technique. The contraction is attributed to reorganization of protein dihedral bonds and of water molecules at relatively long distances from the flavin chromophore, after the protein has received the heat shock from the relaxing photoproduced charge transfer state. This study constitutes a preliminary step towards the understanding of the origin of protein movements taking place upon electron transfer reactions, e.g. between a photoinduced electron donor (or acceptor) and an accepting (or donating) cofactor in a protein.
authors.affiliation: Max-Planck-Institut für Bioanorganische Chemie (formerly Strahlenchemie), Mülheim an der Ruhr, Germany.
authors.forename: Víctor
authors.initials: V
authors.lastname: Martínez-Junza
authors.forename: Alberto C
authors.initials: AC
authors.lastname: Rizzi
authors.forename: Sharmini
authors.initials: S
authors.lastname: Alagaratnam
authors.forename: Toby D M
authors.initials: TD
authors.lastname: Bell
authors.forename: Gerard W
authors.initials: GW
authors.lastname: Canters
authors.forename: Silvia E
authors.initials: SE
authors.lastname: Braslavsky
mesh_terms: D001395:Azotobacter; D002151:Calorimetry; D005415:Flavins / Q000737:chemistry*; D005418:Flavodoxin / Q000737:chemistry*; D007834:Lasers; D055668:Photochemical Processes; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D005415:Flavins; D005418:Flavodoxin