Open AccessDesign of Large Stokes Shift Fluorescent Proteins Based on Excited State Proton Transfer of an Engineered Photobase
Author(s) -
Elizabeth Moreira dos Santos,
Wei Sheng,
Rahele Esmatpour Salmani,
Setare Tahmasebi Nick,
A. Ghanbarpour,
Hadi Gholami,
Chrysoula Vasileiou,
James H. Geiger,
Babak Borhan
Publication year - 2021
Publication title -
journal of the american chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.115
H-Index - 612
eISSN - 1520-5126
pISSN - 0002-7863
DOI - 10.1021/jacs.1c05039
Subject(s) - fluorophore , chemistry , fluorescence , stokes shift , excited state , biophysics , quantum yield , proton , photoexcitation , photochemistry , optics , atomic physics , physics , quantum mechanics , biology
The incredible potential for fluorescent proteins to revolutionize biology has inspired the development of a variety of design strategies to address an equally broad range of photophysical characteristics, depending on potential applications. Of these, fluorescent proteins that simultaneously exhibit high quantum yield, red-shifted emission, and wide separation between excitation and emission wavelengths (Large Stokes Shift, LSS) are rare. The pursuit of LSS systems has led to the formation of a complex, obtained from the marriage of a rationally engineered protein (human cellular retinol binding protein II, hCRBPII) and different fluorogenic molecules, capable of supporting photobase activity. The large increase in basicity upon photoexcitation leads to protonation of the fluorophore in the excited state, dramatically red-shifting its emission, leading to an LSS protein/fluorophore complex. Essential for selective photobase activity is the intimate involvement of the target protein structure and sequence that enables Excited State Proton Transfer (ESPT). The potential power and usefulness of the strategy was demonstrated in live cell imaging of human cell lines.