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Is N 2 O 3 the main nitrosating intermediate in aerated nitric oxide (NO) solutions in vivo ? If so, where, when, and which one?
Author(s) -
Nedospasov Andrei A.
Publication year - 2002
Publication title -
journal of biochemical and molecular toxicology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.526
H-Index - 58
eISSN - 1099-0461
pISSN - 1095-6670
DOI - 10.1002/jbt.10029
Subject(s) - chemistry , nitrite , radical , hydrolysis , homogeneous , in vivo , nitric oxide , polar , aqueous solution , inorganic chemistry , organic chemistry , nitrate , thermodynamics , physics , microbiology and biotechnology , astronomy , biology
The widespread opinion that N 2 O 3 as a product of NO oxidation is the only nitros(yl)ating agent under aerobic conditions is based on experiments in homogeneous buffered water solutions. In vivo NO is oxidized in heterogeneous media and this opinion is not correct. The equilibrium in the system being dependent on temperature and Δ G (sol) for NO, NO 2 , isomers of both N 2 O 3 , and N 2 O 4 . For polar solvents including water, Δ G (sol) for N 2 O 3 is high enough, and a stationary concentration of N 2 O 3 in the mixture with other oxides is sufficient to guarantee the hydrolysis of N 2 O 3 to nitrite. In heterogeneous media, the mixture contains solvates NO 2(sol) , N 2 O 3(sol) , and N 2 O 4(sol) at stationary nonequilibrium concentrations. As far as Δ G (sol) is decreased in heterogeneous mixtures with low polar solvents and/or at increased temperatures, the equilibrium in such a system shifts to NO 2 . Although NO 2 is a reactive free radical, it almost does not react with water. In contrast, the reaction with most functional protein groups efficiently proceeds by a radical type with the formation of nitrite and new radicals (X) further stabilized in various forms. Therefore, the ratio of the nitrosylated and nitrated products yields depends on actual concentrations of all NO x . © 2002 Wiley Periodicals, Inc. J Biochem Mol Toxicol 16:109–120, 2002. DOI 10.1002/jbt.10029