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A comparative picosecond‐resolved fluorescence study of tryptophan residues in iron‐sulfur proteins
Author(s) -
Dorovska-Taran Victoria,
van Hoek Arie,
Link Thomas A.,
Visser Antonie J.W.G.,
Hagen Wilfred R.
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)00606-7
Subject(s) - tryptophan , chemistry , ferredoxin , fluorescence , sulfur , rubredoxin , picosecond , photochemistry , biophysics , redox , crystallography , amino acid , enzyme , biochemistry , inorganic chemistry , organic chemistry , laser , physics , quantum mechanics , optics , biology
The fluorescence intensity and anisotropy decays of the intrinsic tryptophan emission from six Fe/S proteins (ranging from the very simplest ones to enzyme complexes containing one, two or more Trp residues) were measured. All proteins were examined in the reduced and the oxidized state. In either redox state each protein exhibits ultrarapid tryptophan fluorescence decay on the picosecond timescale contributing up to 93% of the total decay. Correlation times in the range of 1 ns or less were found for all six iron‐sulfur proteins reflecting internal Trp motion. In addition, some proteins exhibit longer correlation times reflecting segmental motion and overall protein tumbling. The ultrarapid fluorescence decay in iron‐sulfur proteins indicates efficient radiationless energy transfer between distant tryptophan residues and iron‐sulfur clusters. Such an energy transfer mechanism can be accounted for by referring to the three‐dimensional structures of rubredoxin and ferredoxin in calculating the transfer efficiency of the single tryptophan—iron‐sulfur couple.