Spectroscopy of intermolecular interactions of a tyrosine chromophore. III. Classification of the state of tyrosine residues in proteins based on their electron spectra

Absorption and fluorescence spectra of some tyrosine-containing proteins were analysed. Comparison of the peculiarities of fluorescence and absorption of the tyrosine chromophore in the model compounds and proteins suggested a new classification of the states of tyrosine residues in proteins: I -- tyrosyls with hydrated OH-group (lambda mf approximately equal to 304 nm); II -- tyrosyls, whose hydroxyl group forms the hydrogen bond inside the protein in a hydrophobic surrounding or in the globular fold in structured water layer (lambda mf = 306-307 nm); III -- tyrosyls whose OH-group is deprotonated in the excited state (lambda mf approximately equal to 330-350 nm).