Hypochlorite-induced damage to proteins: formation of nitrogen-centred radicals from lysine residues and their role in protein fragmentation
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Hypochlorite-induced damage to proteins : formation of nitrogen-centred radicals from lysine residues and their role in protein fragmentation. / Hawkins, C L; Davies, Michael Jonathan.
In: Biochemical Journal, Vol. 332 ( Pt 3), 15.06.1998, p. 617-25.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Hypochlorite-induced damage to proteins
T2 - formation of nitrogen-centred radicals from lysine residues and their role in protein fragmentation
AU - Hawkins, C L
AU - Davies, Michael Jonathan
PY - 1998/6/15
Y1 - 1998/6/15
N2 - Stimulated monocytes and neutrophils generate hypochlorite (HOCl) via the release of the enzyme myeloperoxidase and hydrogen peroxide. HOCl damages proteins by reaction with amino acid side-chains or backbone cleavage. Little information is available about the mechanisms and intermediates involved in these reactions. EPR spin trapping has been employed to identify radicals on proteins, peptides and amino acids after treatment with HOCl. Reaction with HOCl gives both high- and low-molecular-mass nitrogen-centred, protein-derived radicals; the yield of the latter increases with both higher HOCl:protein ratios and enzymic digestion. These radicals, which arise from lysine side-chain amino groups, react with ascorbate, glutathione and Trolox. Reaction of HOCl-treated proteins with excess methionine eliminates radical formation, which is consistent with lysine-derived chloramines (via homolysis of N-Cl bonds) being the radical source. Incubation of HOCl-treated proteins, after removal of excess oxidant, gives rise to both nitrogen-centred radicals, over a period of hours, and time-dependent fragmentation of the protein. Treatment with excess methionine or antioxidants (Trolox, ascorbate, glutathione) protects against fragmentation; urate and bilirubin do not. Chloramine formation and nitrogen-centred radicals are therefore key species in HOCl-induced protein fragmentation.
AB - Stimulated monocytes and neutrophils generate hypochlorite (HOCl) via the release of the enzyme myeloperoxidase and hydrogen peroxide. HOCl damages proteins by reaction with amino acid side-chains or backbone cleavage. Little information is available about the mechanisms and intermediates involved in these reactions. EPR spin trapping has been employed to identify radicals on proteins, peptides and amino acids after treatment with HOCl. Reaction with HOCl gives both high- and low-molecular-mass nitrogen-centred, protein-derived radicals; the yield of the latter increases with both higher HOCl:protein ratios and enzymic digestion. These radicals, which arise from lysine side-chain amino groups, react with ascorbate, glutathione and Trolox. Reaction of HOCl-treated proteins with excess methionine eliminates radical formation, which is consistent with lysine-derived chloramines (via homolysis of N-Cl bonds) being the radical source. Incubation of HOCl-treated proteins, after removal of excess oxidant, gives rise to both nitrogen-centred radicals, over a period of hours, and time-dependent fragmentation of the protein. Treatment with excess methionine or antioxidants (Trolox, ascorbate, glutathione) protects against fragmentation; urate and bilirubin do not. Chloramine formation and nitrogen-centred radicals are therefore key species in HOCl-induced protein fragmentation.
KW - Amino Acids
KW - Animals
KW - Antioxidants
KW - Cattle
KW - Chloramines
KW - Electron Spin Resonance Spectroscopy
KW - Electrophoresis, Polyacrylamide Gel
KW - Free Radicals
KW - Humans
KW - Hypochlorous Acid
KW - Lysine
KW - Oligopeptides
KW - Proteins
KW - Serum Albumin
KW - Spin Trapping
KW - Time Factors
M3 - Journal article
C2 - 9620862
VL - 332 ( Pt 3)
SP - 617
EP - 625
JO - Biochemical Journal
JF - Biochemical Journal
SN - 0264-6021
ER -
ID: 138284414