Correlation between internal motion and emission kinetics of tryptophan residues in proteins.

T. Kouyama, K. Kinosita, A. Ikegami

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Abstract

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 degrees 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 (greater than 4 ns) or short (less than 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 (greater than 4 ns). It appears that a tryptophan residue fixed in a polar region has little chance of being quenched by neighboring groups.

Original languageEnglish
Pages (from-to)517-521
Number of pages5
JournalEuropean Journal of Biochemistry
Volume182
Issue number3
Publication statusPublished - 1989 Jul 1
Externally publishedYes

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ASJC Scopus subject areas

  • Biochemistry

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