title: Intermediate Tyrosyl Radical and Amyloid Structure in Peroxide-Activated Cytoglobin.
abstract: We characterized the peroxidase mechanism of recombinant rat brain cytoglobin (Cygb) challenged by hydrogen peroxide, tert-butylhydroperoxide and by cumene hydroperoxide. The peroxidase mechanism of Cygb is similar to that of myoglobin. Cygb challenged by hydrogen peroxide is converted to a Fe4+ oxoferryl π cation, which is converted to Fe4+ oxoferryl and tyrosyl radical detected by direct continuous wave-electron paramagnetic resonance and by 3,5-dibromo-4-nitrosobenzene sulfonate spin trapping. When organic peroxides are used as substrates at initial reaction times, and given an excess of peroxide present, the EPR signals of the corresponding peroxyl radicals precede those of the direct tyrosyl radical. This result is consistent with the use of peroxide as a reducing agent for the recycling of Cygb high-valence species. Furthermore, we found that the Cygb oxidation by peroxides leads to the formation of amyloid fibrils. This result suggests that Cygb possibly participates in the development of degenerative diseases; our findings also support the possible biological role of Cygb related to peroxidase activity.
authors: Departamento de Bioquímica, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors: Juliana C
authors: JC
authors: Ferreira
authors: Departamento de Bioquímica, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors: Marcelo F
authors: MF
authors: Marcondes
authors: Departamento de Bioquímica, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors: Marcelo Y
authors: MY
authors: Icimoto
authors: Departamento de Bioquímica, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors: Thyago H S
authors: TH
authors: Cardoso
authors: Laboratório de Nanoestruturas para Biologia e Materiais Avançados, Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, SP, Brazil.
authors: Aryane
authors: A
authors: Tofanello
authors: Laboratório de Nanoestruturas para Biologia e Materiais Avançados, Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, SP, Brazil.
authors: Felipe S
authors: FS
authors: Pessoto
authors: Laboratório de Nanoestruturas para Biologia e Materiais Avançados, Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, SP, Brazil.
authors: Erica G A
authors: EG
authors: Miranda
authors: Grupo de Biofísica Molecular "Sérgio Mascarenhas," Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil; Laboratório de Nanoestruturas para Biologia e Materiais Avançados, Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, SP, Brazil.
authors: Tatiana
authors: T
authors: Prieto
authors: Grupo de Biofísica Molecular "Sérgio Mascarenhas," Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil.
authors: Otaciro R
authors: OR
authors: Nascimento
authors: Departamento de Bioquímica, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors: Vitor
authors: V
authors: Oliveira
authors: Departamento de Bioquímica, Universidade Federal de São Paulo, São Paulo, SP, Brazil; Laboratório de Nanoestruturas para Biologia e Materiais Avançados, Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, SP, Brazil.
authors: Iseli L
authors: IL
authors: Nantes
mesh_terms: D000682:Amyloid / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D001557:Benzenesulfonates / Q000737:chemistry; D000078842:Cytoglobin; D004578:Electron Spin Resonance Spectroscopy; D005914:Globins / Q000737:chemistry* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007501:Iron / Q000737:chemistry / Q000378:metabolism; D009603:Nitroso Compounds / Q000737:chemistry; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000737:chemistry* / Q000378:metabolism; D051381:Rats
chemical_list: D000682:Amyloid; D001557:Benzenesulfonates; C000627268:Cygb protein, rat; D000078842:Cytoglobin; D009603:Nitroso Compounds; C048757:3,5-dibromo-4-nitrosobenzenesulfonate; D005914:Globins; D006861:Hydrogen Peroxide; D007501:Iron; D009195:Peroxidase