[Intrinsic UV-fluorescence of lysozyme and microenvironment of its tryptophan residues]

The localization of tryptophan residues in hen egg-white lysozyme macromolecule was studied on the basis of the known 3D structure. The polarity and packing density of their microenvironments were evaluated. All residues that can affect the tryptophan fluorescence were revealed. It was shown that the orientation of these active groups relative to the indole ring of tryptophan plays a dramatic role in the efficiency of their influence. Tryptophan--tryptophan nonradiative energy transfer was evaluated from distances between tryptophan residues and their mutual orientation. The conformation of the side chains of tryptophan residues was determined. Special attention was paid to microenvironment of Trp108 responsible for the minor absorption band at 305 nm.