Mapping the Complete Photocycle that Powers a Large Stokes Shift Red Fluorescent Protein.
Angew Chem Int Ed Engl
; 62(5): e202212209, 2023 01 26.
Article
em En
| MEDLINE
| ID: mdl-36440527
ABSTRACT
Large Stokes shift (LSS) red fluorescent proteins (RFPs) are highly desirable for bioimaging advances. The RFP mKeima, with coexisting cis- and trans-isomers, holds significance as an archetypal system for LSS emission due to excited-state proton transfer (ESPT), yet the mechanisms remain elusive. We implemented femtosecond stimulated Raman spectroscopy (FSRS) and various time-resolved electronic spectroscopies, aided by quantum calculations, to dissect the cis- and trans-mKeima photocycle from ESPT, isomerization, to ground-state proton transfer in solution. This work manifests the power of FSRS with global analysis to resolve Raman fingerprints of intermediate states. Importantly, the deprotonated trans-isomer governs LSS emission at 620â
nm, while the deprotonated cis-isomer's 520â
nm emission is weak due to an ultrafast cis-to-trans isomerization. Complementary spectroscopic techniques as a table-top toolset are thus essential to study photochemistry in physiological environments.
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Base de dados:
MEDLINE
Assunto principal:
Prótons
/
Análise Espectral Raman
Idioma:
En
Ano de publicação:
2023
Tipo de documento:
Article