Tyrosyl Fluorescence Spectra of Proteins Lacking Tryptophan: Effects of Intramolecular Interactions

The fluorescence spectra of class A proteins which lack tryptophanyl residues were examined in detail, and revealed some differences in the position of maximum and half‐width of the tyrosine emission band between proteins and tyrosine itself. These parameters were affected by conformational changes in protein molecules (denaturation, thermal effects, ion binding) which also induced variations in absorption spectra and fluorescence quantum yields. These observations are thought to be related to the formation of hydrogen bonds between the hydroxyl group of the tyrosyl residues and proton acceptor groups in the protein.