title: The effect of pH on the oxidation of bovine serum albumin by hypervalent myoglobin species.
abstract: Bovine serum albumin (BSA) was used as a probe for the oxidation of proteins by hypervalent myoglobin species in solutions with pH from 5.3 to 7.7. The reaction between perferrylmyoglobin, *MbFe(IV)=O, and BSA was studied by activating metmyoglobin with equimolar amounts of hydrogen peroxide in the presence of BSA. A minor pH dependence was observed as judged from the formation of BSA-centered radicals, which were monitored at room temperature by electron spin resonance spectroscopy, and the formation of dityrosine. The reaction between ferrylmyoglobin, MbFe(IV)=O, and BSA was pH-dependent. BSA-centered radicals and dityrosine were formed in low levels at neutral pH and increased at low pH to the same levels as observed in the reaction of *MbFe(IV)=O with BSA. The present results demonstrate that protein-centered radicals can be formed from the non-radical MbFe(IV)=O under mildly acidic conditions, and this should be taken into account when considering oxidation in cellular compartments of low pH and in meat-related products.
authors.affiliation: Food Chemistry, Department of Dairy and Food Science, The Royal Veterinary and Agricultural University, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark. mola@kvl.dk
authors.forename: Maiken V
authors.initials: MV
authors.lastname: Kröger-Ohlsen
authors.forename: Henrik
authors.initials: H
authors.lastname: Østdal
authors.forename: Mogens L
authors.initials: ML
authors.lastname: Andersen
mesh_terms: D000818:Animals; D002417:Cattle; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D006736:Horses; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D046911:Macromolecular Substances; D008786:Metmyoglobin / Q000737:chemistry*; D010084:Oxidation-Reduction; D011485:Protein Binding; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000138:chemical synthesis*
chemical_list: D046911:Macromolecular Substances; D012996:Solutions; C028048:ferrylmyoglobin; D008786:Metmyoglobin; D012710:Serum Albumin, Bovine; D014443:Tyrosine; D006861:Hydrogen Peroxide; C007543:dityrosine