Conformational Homogeneity in the Pr Isomer of Phytochrome Cph1.
J Phys Chem B
; 121(12): 2622-2630, 2017 03 30.
Article
em En
| MEDLINE
| ID: mdl-28282147
ABSTRACT
Numerous time-resolved studies of the Pr to Pfr photoisomerization 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 Pr to Lumi-R occurs adiabatically on the excited-state potential energy surface.
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1
Base de dados:
MEDLINE
Assunto principal:
Fitocromo
/
Proteínas Quinases
/
Proteínas de Bactérias
/
Synechocystis
Idioma:
En
Ano de publicação:
2017
Tipo de documento:
Article