Open AccessCorrelation between internal motion and emission kinetics of tryptophan residues in proteins
Author(s) -
KOUYAMA Tsutomu,
KINOSITA Kazuhiko,
IKEGAMI Akira
Publication year - 1989
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1989.tb14858.x
Subject(s) - tryptophan , residue (chemistry) , chemistry , kinetics , fluorescence , nanosecond , fluorescence anisotropy , biophysics , biochemistry , amino acid , optics , biology , physics , laser , quantum mechanics , membrane
Time‐resolved fluorescence anisotropy measurements of tryptophan residues were carried out for 44 proteins. Internal rotational motion with a sub‐nanosecond correlation time (0.9 ± 0.6 ns at 10°C) was seen in a large number of proteins, though its amplitude varied from protein to protein. It was found that tryptophan residues which were almost fixed within a protein had either a long (> 4 ns) or short (< 2 ns) fluorescence lifetime, whereas a residue undergoing a large internal motion had an intermediate lifetime (1.5–3 ns). It is suggested that the emission kinetics of a tryptophan residue is coupled with its internal motion. In particular, an immobile tryptophan residue emitting at long wavelength was characterized by a long lifetime (>4 ns). It appears that a tryptophan residue fixed in a polar region has little chance of being quenched by neighboring groups.