title: Protection of ceruloplasmin by lactoferrin against hydroxyl radicals is pH dependent.
abstract: Destruction of ceruloplasmin (Cp) in the presence of hydrogen peroxide is accompanied by the release of the protein's copper ions that provoke formation of hydroxyl radicals (OH˙) and, consequently, further degradation of the protein. Under such conditions, degradation of Cp is hampered by a number of substances able to bind copper ions. Lactoferrin (Lf) is the most active protector of Cp, its protective effect depending on the pH of the medium. The best protection of Cp by Lf was detected at pH 7.4. In an acidic buffer (pH 5.5), Lf did not affect the destruction of Cp. The pH-dependent efficiency of copper binding by Lf is in good agreement with its capacity to protect Cp against degradation provoked by hydrogen peroxide. It seems likely that peroxide-dependent degradation of Cp stimulated by its own copper ions is a part of neutrophil-induced antimicrobial reactions and may take place properly at the foci of inflammation. Interaction of Lf with Cp may regulate the generation of OH˙ from hydrogen peroxide in the foci of inflammation and protect the adjacent tissues.
authors.affiliation: Institute for Experimental Medicine, N-W Branch of the Russian Academy of Medical Sciences, 197376 Saint-Petersburg, Acad. Pavlov street 12, Russia. biochemsokolov@gmail.com
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Sokolov
authors.forename: Kirill V
authors.initials: KV
authors.lastname: Solovyov
authors.forename: Valeria A
authors.initials: VA
authors.lastname: Kostevich
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Chekanov
authors.forename: Maria O
authors.initials: MO
authors.lastname: Pulina
authors.forename: Elena T
authors.initials: ET
authors.lastname: Zakharova
authors.forename: Mikhail M
authors.initials: MM
authors.lastname: Shavlovski
authors.forename: Oleg M
authors.initials: OM
authors.lastname: Panasenko
authors.forename: Vadim B
authors.initials: VB
authors.lastname: Vasilyev
mesh_terms: D002570:Ceruloplasmin / Q000737:chemistry*; D003300:Copper / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D017665:Hydroxyl Radical / Q000737:chemistry*; D007781:Lactoferrin / Q000737:chemistry*; D009113:Muramidase / Q000737:chemistry; D016877:Oxidants / Q000737:chemistry; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011485:Protein Binding; D059748:Proteolysis; D012709:Serum Albumin / Q000737:chemistry
chemical_list: D016877:Oxidants; D012709:Serum Albumin; D017665:Hydroxyl Radical; D003300:Copper; D006861:Hydrogen Peroxide; D002570:Ceruloplasmin; D009113:Muramidase; D007781:Lactoferrin