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Polarized luminescence and mobility of tryptophan residues in polypeptide chains
Author(s) -
Semisotnov G. V.,
Zikherman K. Kh.,
Kasatkin S. B.,
Ptitsyn O. B.,
Anufrieva E. V.
Publication year - 1981
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1981.360201102
Subject(s) - tryptophan , chemistry , side chain , luminescence , isomerization , optical rotatory dispersion , indole test , crystallography , stereochemistry , photochemistry , amino acid , circular dichroism , organic chemistry , biochemistry , polymer , physics , optoelectronics , catalysis
Polarized luminescence was used to study the mobility of tryptophan residues in polypeptide chains of different chemical composition and structural organization. It has been shown that the luminescence depolarization of tryptophan residues in coillike, helical, and β‐structural polypeptide chains is mainly caused by “fast” torsional vibrations and “slow” rotational isomerization of indole groups of tryptophan side chains. The characteristics of these types of motions are practically the same for tryptophan residues included in coillike chains of different chemical structure. Helix–coil transitions in copolymers of glutamic acid and lysine with tryptophan (Glu, Trp) and (Lys, Trp) (where side groups of tryptophan residues weakly interact with the surrounding side groups) do not appreciably change the amplitude of torsional vibrations or rotational isomerization. At the same time, in the helical state of glutamic acid–leucine–tryptophan copolymers (Glu, Leu, Trp) and in the β‐structural state of (Lys, Trp) copolymers (where direct interactions of Trp side groups with other side groups are possible), the amplitudes of the torsional vibrations are smaller and the rotational isomerization times larger than in the coil. The transition of (Glu, Leu, Trp) polypeptide chains into a compact state is accompanied by a marked decrease of both “fast” and “slow” intra‐molecular mobility and by an increase of the contribution made by the rotation of the macromolecule as a whole, as shown by the decrease of the luminescence polarization.