title: Superoxide radicals can act synergistically with hypochlorite to induce damage to proteins.
abstract: Activated phagocytes generate both superoxide radicals via a respiratory burst, and HOCl via the concurrent release of the haem enzyme myeloperoxidase. Amine and amide functions on proteins and carbohydrates are major targets for HOCl, generating chloramines (RNHCl) and chloramides (RC(O)NClR'), which can accumulate to high concentrations (>100 microM). Here we show that superoxide radicals catalyse the decomposition of chloramines and chloramides to reactive nitrogen-centred radicals, and increase the extent of protein fragmentation compared to that observed with either superoxide radicals or HOCl, alone. This synergistic action may be of significance at sites of inflammation, where both superoxide radicals and chloramines/chloramides are formed simultaneously.
authors.affiliation: The EPR Group, Heart Research Institute, Camperdown, Sydney, NSW 2050, Australia.
authors.forename: Clare L
authors.initials: CL
authors.lastname: Hawkins
authors.forename: Martin D
authors.initials: MD
authors.lastname: Rees
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Davies
mesh_terms: D002700:Chloramines / Q000378:metabolism; D004357:Drug Synergism; D006997:Hypochlorous Acid / Q000494:pharmacology*; D011506:Proteins / Q000187:drug effects* / Q000378:metabolism; D026361:Reactive Nitrogen Species / Q000378:metabolism; D012710:Serum Albumin, Bovine / Q000187:drug effects / Q000378:metabolism; D013481:Superoxides / Q000494:pharmacology*
chemical_list: D002700:Chloramines; D011506:Proteins; D026361:Reactive Nitrogen Species; D013481:Superoxides; D012710:Serum Albumin, Bovine; D006997:Hypochlorous Acid