Metabolism of aromatic amines by prostaglandin H synthase
The metabolism of aromatic amines by the peroxidase activity of prostaglandin H synthase (PHS) has been studied in this laboratory by use of two model compounds, the carcinogenic primary amine 2-aminofluorene (2-AF) and the substituted amine aminopyrine (AP). 2-AF is oxidized by PHS to 2, 2-azobisfluorene, 2-aminodifluorenylamine, 2-nitrofluorene, polymeric material, and products covalently bound to macromolecules. In the presence of phenolic compounds, 2-AF oxidation results in the formation of amine-phenol adducts. The data are consistent with a one-electron mechanism of 2-AF oxidation by PHS; furthermore, an N-hydroxy intermediate is not involved in 2-AF metabolism by PHS. PHS also catalyzes the binding of 2-AF to DNA in vitro. Unique 2-AF/DNA adducts were isolated and are distinct from the N-(deoxyguanosin-8-yl)-2-AF adduct formed from the reaction of N-hydroxy-2-AF with DNA. These new adducts represent a marker unique to peroxidative activation of 2-AF. AP is oxidized by the peroxidase activity of PHS to the cation radical, with one molecule of hydroperoxy fatty acid reduced for every two molecules of AP free radical formed. The decay of the AP radical follows second order kinetics, supporting the proposed mechanism in which the AP radical disproportionates to an iminium cation, followed by hydrolysis of this species to the demethylated amine and formaldehyde. In the presence of glutathione, the cation radical is reduced to the parent amine, resulting in the formation of the glutathione thiyl radical. It thus appears that both primary and substituted aromatic amines may undergo one-electron oxidation by PHS. 19 references.
- Research Organization:
- National Institute of Environmental Health Sciences, Research Triangle Park, NC
- OSTI ID:
- 5243310
- Journal Information:
- Environ. Health Perspect.; (United States), Vol. 64
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PEROXIDASES
BIOCHEMICAL REACTION KINETICS
POLYCYCLIC AROMATIC AMINES
METABOLISM
PROSTAGLANDINS
ENZYME ACTIVITY
ADDUCTS
CARBOXYLIC ACIDS
CARCINOGENS
CATALYSIS
CATIONS
CHEMICAL ACTIVATION
CHEMICAL BONDS
DNA
ENZYMES
FORMALDEHYDE
HYDROLYSIS
IN VITRO
OXIDATION
PHENOLS
RADICALS
REACTION INTERMEDIATES
ALDEHYDES
AMINES
AROMATICS
CHARGED PARTICLES
CHEMICAL REACTIONS
DECOMPOSITION
HYDROXY COMPOUNDS
IONS
KINETICS
LYSIS
NUCLEIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
REACTION KINETICS
SOLVOLYSIS
560300* - Chemicals Metabolism & Toxicology