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Tryptophan mediated photoreduction of disulfide bond causes unusual fluorescence behaviour of Fusarium solani pisi cutinase
Author(s) -
Prompers Jeanine J.,
Hilbers Cornelis W.,
Pepermans Henri A.M.
Publication year - 1999
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/s0014-5793(99)00990-4
Subject(s) - cutinase , tryptophan , chemistry , photochemistry , fluorescence , residue (chemistry) , covalent bond , peptide bond , hydrogen bond , cysteine , enzyme , stereochemistry , organic chemistry , biochemistry , amino acid , molecule , physics , quantum mechanics
The fluorescence signal of the single tryptophan residue (Trp 69 ) of Fusarium solani pisi cutinase is highly quenched. However, prolonged irradiation of the enzyme in the tryptophan absorption band causes an increase of the tryptophan fluorescence quantum yield by an order of magnitude. By using a combination of NMR spectroscopy and chemical detection of free thiol groups with a sulfhydryl reagent we could unambiguously show that the unusual fluorescence behaviour of Trp 69 in cutinase is caused by the breaking of the disulfide bond between Cys 31 and Cys 109 upon irradiation, while the amide‐aromatic hydrogen bond between Ala 32 and Trp 69 remains intact. This is the first example of tryptophan mediated photoreduction of a disulfide bond in proteins.