Time-Resolved Spectroscopy of Proteins

changes upon e.g. unfolding, substrate binding or Optical absorption of proteins in the region of 250other catalytical processes. Furthermore, single Trp 300 nm (near-UV) is governed by the aromatic mutants provide the possibility to examine protein amino acid residues phenylalanine (Phe), tyrosine dynamic at individual sites of the protein with time(Tyr) and tryptophan (Trp) [1]. Compared with Tyr resolved fluorescence spectroscopy. In this and Trp the absorbance of Phe in the near-UV as application note we demonstrate the potential of well as its quantum yield is negligible (Fig. 1A). nowadays commercially available lifetime Consequently, the observed protein fluorescence is spectrometers and mention the limitations of such a mainly caused by Trp and Tyr residues. When spectrometer with sub-nanosecond resolution for excited between 290-295 nm the emission of determining dynamic processes in proteins. proteins is generally dominated by the Trp