[What determines the characteristics of the intrinsic UV-fluorescence of proteins? Analysis of the properties of the microenvironment and features of the localization of their tryptophan residues].

To elucidate the dependence of protein intrinsic fluorescence characteristics on the microenvironment of their tryptophan residue localization, more than a hundred tryptophan residues of a number of proteins were analysed and compared with experimental data on their intrinsic fluorescence. Some factors were revealed, which determine the fluorescence spectrum position of certain tryptophan residues and their contribution to the total protein fluorescence. Specifically, the role of aromatic residues and proline, as well as of tryptophan residue side chain conformation, in the formation of the unique blue fluorescence spectrum of a number of proteins was demonstrated. It was shown that the quenching effect of sulphur atoms of cysteine and methionine, imidazole rings of histidine, guanyl groups of arginine, etc. depends not only on their distance from the indole ring of the tryptophan residue but, to a great extent, on their orientation to indole ring.