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Product Distribution of Peroxynitrite Decay as a Function of pH, Temperature, and Concentration

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posted on 19.12.2001 by Reinhard Kissner, Willem H. Koppenol
The decay of peroxynitrite [ONOO-, oxoperoxonitrate(1−)] was examined as a function of concentration (0.050−2.5 mM), temperature (5−45 °C), and pH (2.2−10.0). Below 5 °C and pH 7, little amounts of the decomposition products nitrite and dioxygen are formed, even when the peroxynitrite concentration is high (2.5 mM). Instead, approximately ≥90% isomerizes to nitrate. At higher pH, decomposition increases at the expense of isomerization, up to nearly 80% at pH 10.0 at 5 °C and 90% at 45 °C. Much less nitrite and dioxygen per peroxynitrite are formed when the peroxynitrite concentration is lower; at 50 μM and pH 10.2, ≤40% decomposes. In contrast to two other reports (Pfeiffer, S.; Gorren, A. C. F.; Schmidt, K.; Werner, E. R.; Hansert, B.; Bohle, D. S.; Mayer, B. J. Biol. Chem. 1997, 272, 3465−3470, and Coddington, J. W.; Hurst, J. K.; Lymar, S. V. J. Am. Chem. Soc. 1999, 121, 2438−2443), we find that the extent of decomposition is dependent on the peroxynitrite concentration.

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