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Resolved Fluorescence of the Two Tryptophan Residues in Horse Apomyoglobin
Author(s) -
Glandières JeanMarie,
Twist Charles,
Haouz Ahmed,
Zentz Christian,
Alpert Bernard
Publication year - 2000
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/0031-8655(2000)0710382rfottt2.0.co2
Subject(s) - fluorescence , chemistry , tryptophan , quenching (fluorescence) , residue (chemistry) , iodide , photochemistry , titration , emission spectrum , analytical chemistry (journal) , spectral line , chromatography , inorganic chemistry , biochemistry , optics , amino acid , physics , astronomy
The composite fluorescence emission from the two tryptophans (W 7 and W 14 ) of horse heart apomyoglobin was explored by fluorescence quenching experiments. The fluorescence of the W 7 residue is the only one involved in the quenching by iodide or trichloroethanol (TCE) titration. The fluorescence contribution of W 7 is 49% of the total apomyoglobin emission, and its spectrum is red‐shifted compared to the W 14 emission. The fluorescence decay of Trp residues gives an average fluorescence lifetime of 2.06 ns for W 14 and 2.84 ns for W 7 . The static fluorescence quenching by TCE was used to monitor the individual motions of the two tryptophans in apomyoglobin. The short correlation time of W 7 (ρ= 3 ns) explains why this residue can experience various environments without having to assume the existence of several protein conformations occurring during its lifetime emission.