Fluorescence contributions of the individual Trp residues in goat α-lactalbumin

Ann Vanhooren, Eszter Illyes, Zs. Majer, Ignace Hanssens

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Goat α-lactalbumin (GLA) contains four tryptophan (Trp) residues. In order to obtain information on the fluorescence contribution of the individual Trp residues in native GLA, we recorded the fluorescence spectra of four GLA mutants, W26F, W60F, W104F, and W118F, in each of which a single Trp residue was replaced with phenylalanine (Phe). Comparison of the fluorescence spectra of the four mutants with that of wild-type GLA indicated that, in native GLA, three Trp residues (Trp60, Trp104, and Trp118) are strongly quenched and account for the partial indirect quenching of Trp26. As a consequence, the fluorescence of wild-type GLA and of the mutants W60F, W104F, and W118F mainly results from Trp26. An inspection of the crystal structure indicated that, in addition to the disulfide bonds that are in direct contact with the indole groups of Trp60 and Trp118, backbone peptide bonds that are in direct contact with the indole groups of Trp60, Trp104, and Trp118, contribute to the direct quenching effects. Interestingly, the lack of direct quenching of Trp26 explains why the cleavage of disulfide bonds by UV light is mediated more by the highly fluorescent Trp26 than by the less fluorescent Trp104 and Trp118.

Original languageEnglish
Pages (from-to)1586-1591
Number of pages6
JournalBiochimica et Biophysica Acta - Proteins and Proteomics
Volume1764
Issue number10
DOIs
Publication statusPublished - Oct 2006

Fingerprint

Lactalbumin
Goats
Tryptophan
Fluorescence
Quenching
Disulfides
Ultraviolet Rays
Phenylalanine
Ultraviolet radiation
Crystal structure
Inspection
Peptides

Keywords

  • Alpha-lactalbumin
  • Differential scanning calorimetry
  • Disulfide bond
  • Photolysis
  • Trp-Phe mutant
  • Tryptophan fluorescence

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Genetics

Cite this

Fluorescence contributions of the individual Trp residues in goat α-lactalbumin. / Vanhooren, Ann; Illyes, Eszter; Majer, Zs.; Hanssens, Ignace.

In: Biochimica et Biophysica Acta - Proteins and Proteomics, Vol. 1764, No. 10, 10.2006, p. 1586-1591.

Research output: Contribution to journalArticle

Vanhooren, Ann ; Illyes, Eszter ; Majer, Zs. ; Hanssens, Ignace. / Fluorescence contributions of the individual Trp residues in goat α-lactalbumin. In: Biochimica et Biophysica Acta - Proteins and Proteomics. 2006 ; Vol. 1764, No. 10. pp. 1586-1591.
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