Site-specific fragmentation and modification of albumin by sulfite in the presence of metal ions or peroxidase/H2O2: role of sulfate radical.
Exposure of albumin to sulfite in the presence of Co(II) or peroxidase/H2O2 caused site-specific fragmentation, which was not due to cleavage of methionyl nor tryptophanyl peptide bonds. The reaction of GlyPro with sulfite in the presence of Co(II) or peroxidase/H2O2 led to Gly liberation, suggesting the oxidative cleavage of protein at Pro residues. Sulfite plus Co(II) induced bityrosine production, Trp loss and a new Trp-derived fluorescence. ESR-spin trapping method provided evidence for the formation of sulfate radical (SO4.-) during Co(II)-catalyzed autoxidation of sulfite. The order of reactivity with SO4.- seemed to be Trp greater than GlyPro greater than GlyGly approximately Gly approximately Pro. The results suggest that SO4.- plays an important role in fragmentation and modification of albumin.
Ito
K
K
Department of Public Health, Faculty of Medicine, Kyoto University, Japan.
Kawanishi
S
S
D000818:Animals; D003300:Copper / Q000494:pharmacology*; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D006735:Horseradish Peroxidase / Q000494:pharmacology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D007700:Kinetics; D010782:Photolysis; D012709:Serum Albumin / Q000187:drug effects / Q000378:metabolism*; D012710:Serum Albumin, Bovine / Q000187:drug effects / Q000378:metabolism; D013431:Sulfates; D013447:Sulfites / Q000494:pharmacology*; D013464:Sulfuric Acids
D005609:Free Radicals; D012709:Serum Albumin; D013431:Sulfates; D013447:Sulfites; D013464:Sulfuric Acids; C069025:sulfate radical; D012710:Serum Albumin, Bovine; D003300:Copper; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase