title: Sub-picosecond mid-infrared spectroscopy of phytochrome Agp1 from Agrobacterium tumefaciens.
abstract: The photoinduced primary reaction of the biliverdin binding phytochrome Agp1 (Agp1-BV) from Agrobacterium tumefaciens was investigated by sub-picosecond time-resolved Vis pump-IR probe spectroscopy. Three time constants of tau(1)=0.7+/-0.05 ps, tau(2)=3.3+/-0.2 ps and tau(3)=33.3+/-1.5 ps could be isolated from the dynamics of structurally specific marker bands of the BV chromophore. These results together with those of accompanying sub-picosecond Vis pump-Vis probe spectroscopy allow the extension of the reaction scheme for the primary process by a vibrationally excited electronic ground state. The isomerization at the C15=C16 bond occurs within the lifetime of the excited electronic state. A quantum yield of 0.094 for the primary reaction is determined, suggesting that the quantum yield of formation of the P(fr) far-red-absorbing form is already established in the primary photoreaction of the P(r) (red-absorbing) form.
authors.affiliation: Technische Universität Kaiserslautern, Fachbereich Physik, 67653 Kaiserslautern, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Schumann
authors.forename: Ruth
authors.initials: R
authors.lastname: Gross
authors.forename: Norbert
authors.initials: N
authors.lastname: Michael
authors.forename: Tilman
authors.initials: T
authors.lastname: Lamparter
authors.forename: Rolf
authors.initials: R
authors.lastname: Diller
mesh_terms: D016960:Agrobacterium tumefaciens / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D001664:Biliverdine / Q000737:chemistry; D010834:Phytochrome / Q000378:metabolism*; D013055:Spectrophotometry, Infrared / Q000379:methods
chemical_list: D001426:Bacterial Proteins; D010834:Phytochrome; D001664:Biliverdine