Tryptophan residues are targets in hypothiocyanous acid-mediated protein oxidation
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Tryptophan residues are targets in hypothiocyanous acid-mediated protein oxidation. / Hawkins, Clare Louise; Pattison, David I; Stanley, Naomi R; Davies, Michael Jonathan.
I: Biochemical Journal, Bind 416, Nr. 3, 15.12.2008, s. 441-52.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Tryptophan residues are targets in hypothiocyanous acid-mediated protein oxidation
AU - Hawkins, Clare Louise
AU - Pattison, David I
AU - Stanley, Naomi R
AU - Davies, Michael Jonathan
PY - 2008/12/15
Y1 - 2008/12/15
N2 - Myeloperoxidase, released by activated phagocytes, forms reactive oxidants by catalysing the reaction of halide and pseudo-halide ions with H(2)O(2). These oxidants have been linked to tissue damage in a range of inflammatory diseases. With physiological levels of halide and pseudo-halide ions, similar amounts of HOCl (hypochlorous acid) and HOSCN (hypothiocyanous acid) are produced by myeloperoxidase. Although the importance of HOSCN in initiating cellular damage via thiol oxidation is becoming increasingly recognized, there are limited data on the reactions of HOSCN with other targets. In the present study, the products of the reaction of HOSCN with proteins has been studied. With albumin, thiols are oxidized preferentially forming unstable sulfenyl thiocyanate derivatives, as evidenced by the reversible incorporation of (14)C from HOS(14)CN. On consumption of the HSA (human serum albumin) free thiol group, the formation of stable (14)C-containing products and oxidation of tryptophan residues are observed. Oxidation of tryptophan residues is observed on reaction of HOSCN with other proteins (including myoglobin, lysozyme and trypsin inhibitor), but not free tryptophan, or tryptophan-containing peptides. Peptide mass mapping studies with HOSCN-treated myoglobin, showed the addition of two oxygen atoms on either Trp(7) or Trp(14) with equimolar or less oxidant, and the addition of a further two oxygen atoms to the other tryptophan with higher oxidant concentrations (> or = 2-fold). Tryptophan oxidation was observed on treating myoglobin with HOSCN in the presence of glutathione and ascorbate. Thus tryptophan residues are likely to be favourable targets for the reaction in biological systems, and the oxidation products formed may be useful biomarkers of HOSCN-mediated protein oxidation.
AB - Myeloperoxidase, released by activated phagocytes, forms reactive oxidants by catalysing the reaction of halide and pseudo-halide ions with H(2)O(2). These oxidants have been linked to tissue damage in a range of inflammatory diseases. With physiological levels of halide and pseudo-halide ions, similar amounts of HOCl (hypochlorous acid) and HOSCN (hypothiocyanous acid) are produced by myeloperoxidase. Although the importance of HOSCN in initiating cellular damage via thiol oxidation is becoming increasingly recognized, there are limited data on the reactions of HOSCN with other targets. In the present study, the products of the reaction of HOSCN with proteins has been studied. With albumin, thiols are oxidized preferentially forming unstable sulfenyl thiocyanate derivatives, as evidenced by the reversible incorporation of (14)C from HOS(14)CN. On consumption of the HSA (human serum albumin) free thiol group, the formation of stable (14)C-containing products and oxidation of tryptophan residues are observed. Oxidation of tryptophan residues is observed on reaction of HOSCN with other proteins (including myoglobin, lysozyme and trypsin inhibitor), but not free tryptophan, or tryptophan-containing peptides. Peptide mass mapping studies with HOSCN-treated myoglobin, showed the addition of two oxygen atoms on either Trp(7) or Trp(14) with equimolar or less oxidant, and the addition of a further two oxygen atoms to the other tryptophan with higher oxidant concentrations (> or = 2-fold). Tryptophan oxidation was observed on treating myoglobin with HOSCN in the presence of glutathione and ascorbate. Thus tryptophan residues are likely to be favourable targets for the reaction in biological systems, and the oxidation products formed may be useful biomarkers of HOSCN-mediated protein oxidation.
KW - Amino Acid Sequence
KW - Antioxidants
KW - Ascorbic Acid
KW - Fluorescent Dyes
KW - Glutathione
KW - Humans
KW - Hypochlorous Acid
KW - Molecular Sequence Data
KW - Molecular Structure
KW - Myoglobin
KW - Oxidation-Reduction
KW - Peptide Fragments
KW - Peptide Mapping
KW - Protein Denaturation
KW - Serum Albumin
KW - Sulfhydryl Compounds
KW - Thiocyanates
KW - Tryptophan
U2 - 10.1042/BJ20070941
DO - 10.1042/BJ20070941
M3 - Journal article
C2 - 18652572
VL - 416
SP - 441
EP - 452
JO - Biochemical Journal
JF - Biochemical Journal
SN - 0264-6021
IS - 3
ER -
ID: 129670687