title: Conformational Homogeneity in the PrIsomer of Phytochrome Cph1.
abstract: Numerous time-resolved studies of the Prto Pfrphotoisomerization in phytochrome Cph1 have revealed multiphasic excited-state decay kinetics. It remains unclear whether these kinetics arise from multiple ground-state conformational subpopulations or from a single ground-state conformation that undergoes an excited-state photoisomerization process-either branching on the excited state or relaxing through multiple sequential intermediates. Many studies have attempted to resolve this debate by fitting the measured dynamics to proposed kinetic models, arriving at different conclusions. Here we probe spectral signatures of ground-state heterogeneity of Pr. Two-dimensional electronic spectra display negligible inhomogeneous line broadening, and vibrational coherence spectra extracted from transient absorption measurements do not contain nodes and phase shifts at the fluorescence maximum. These spectroscopic results support the homogeneous model, in which the primary photochemical transformation of Prto Lumi-R occurs adiabatically on the excited-state potential energy surface.
authors.affiliation: Department of Chemistry, New York University , 100 Washington Square East, New York, New York 10003, United States.
authors.forename: Laurie A
authors.initials: LA
authors.lastname: Bizimana
authors.affiliation: Department of Chemistry, New York University , 100 Washington Square East, New York, New York 10003, United States.
authors.forename: Jordan
authors.initials: J
authors.lastname: Epstein
authors.affiliation: Department of Chemistry, New York University , 100 Washington Square East, New York, New York 10003, United States.
authors.forename: Johanna
authors.initials: J
authors.lastname: Brazard
authors.affiliation: Department of Chemistry, New York University , 100 Washington Square East, New York, New York 10003, United States.
authors.forename: Daniel B
authors.identifier: 0000-0002-3148-5317
authors.initials: DB
authors.lastname: Turner
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D007536:Isomerism; D007700:Kinetics; D056004:Molecular Dynamics Simulation; D055668:Photochemical Processes; D020283:Photoreceptors, Microbial; D010834:Phytochrome / Q000737:chemistry*; D011487:Protein Conformation; D011494:Protein Kinases / Q000737:chemistry*; D046939:Synechocystis / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D020283:Photoreceptors, Microbial; D010834:Phytochrome; D011494:Protein Kinases; C413623:Cph1 phytochrome protein, bacteria