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Peroxynitrite formation from the simultaneous reduction of nitrite and oxygen by xanthine oxidase
Author(s) -
Millar Timothy M.
Publication year - 2004
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(04)00218-2
Subject(s) - peroxynitrite , xanthine oxidase , chemistry , nitrite , biochemistry , xanthine , oxygen , xanthine dehydrogenase , superoxide , enzyme , organic chemistry , nitrate
One electron reductions of oxygen and nitrite by xanthine oxidase form peroxynitrite. The nitrite and oxygen reducing activities of xanthine oxidase are regulated by oxygen with K oxygen 26 and 100 μM and K nitrite 1.0 and 1.1 mM with xanthine and NADH as donor substrates. Optimal peroxynitrite formation occurs at 70 μM oxygen with purine substrates. Kinetic parameters: V max ∼50 nmol/min/mg and K m of 22, 36 and 70 μM for hypoxanthine, pterin and nitrite respectively. Peroxynitrite generation is inhibited by allopurinol, superoxide dismutase and diphenylene iodonium. A role for this enzyme activity can be found in the antibacterial activity of milk and circulating xanthine oxidase activity.