Genetically Incorporable, Tryptophan-Based Cyan Fluorescent Amino Acid for Protein Spectroscopy and Microscopy
6-acetyl-L-tryptophan (6Ac-Trp) was synthesized as a tryptophan (Trp) analog with an absorption spectrum extending to ca. 400 nm, an emission spectrum spanning the blue-to-green visible region. Its fluorescence quantum yield is environment-sensitive (i.e., ca. 0.54 in water and <0.01 in hydrophobic solvents). A highl...