Photoisomerization of the green fluorescence protein chromophore and the meta- and para-amino analogues

Abstract

The Z --> E photoisomerization and fluorescence quantum yields for the wild-type green fluorescence protein (GFP) chromophore (p-HBDI) and its meta- and para-amino analogues (m-ABDI and p-ABDI) in aprotic solvents (hexane, THF, and acetonitrile) and protic solvents (methanol and 10-20% H(2)O in THF) are reported. The dramatic decrease in the quantum yields on going from aprotic to protic solvents indicates the important role of solvent-solute hydrogen bonding in the nonradiative decay pathways. The enhanced fluorescence of m-ABDI is also discussed.