Non-Aromatic Fluorescence from Single α-Helical Peptides

We describe the first systematic analysis of NAF-emitting peptides in solution and show that short peptides derived from zwitterionic single α-helices (SAHs), formed exclusively by non-aromatic lysine and glutamic acid residues, are UV-active and luminescent at near-UV wavelengths in solution (λexc = 320 nm; λem ≈ 420 nm). We also show that their emission depends on the α helical folding, which favors intramolecular through-space interactions between the Lys/Glu side chains and that conservative mutations, such as the replacement of Lys by Orn or Arg, strongly influence the NAF emission.