Tyrosine nitration and peroxonitrite (peroxynitrite) isomerisation: 15N CIDNP NMR studies

15N Chemically Induced Dynamic Nuclear Polarization (15N‐CIDNP) Investigations of the Peroxynitrite Decay and Nitration of N‐Acetyl‐L‐tyrosine

“…30% hydroxyl radicals and nitrogen dioxide during the peroxynitrite decay [2] [12] and of 30 -33% NOC 2 and COC À 3 radicals from the decomposition of the peroxynitriteÀCO 2 adduct [11] [13] [14]. Butler and co-workers were able to establish the existence of solvent cages by the observation of [15]. However, there are two puzzling observations which cannot be explained by using Scheme 2 without further assumptions.…”

“…The first one is the missing of 3-NO 2 -Tyr formation. The second one is the lack of 15 N-CIDNP effects in the absence of Tyr. For explaining these results, it has to be considered that the validity of Scheme 2 has been proven under physiological conditions.…”

“…It seems very likely that, for understanding the 15 N-CIDNP observations, additional reactions have to be taken into account. The purpose of this report is to get a better understanding of the 15 N-CIDNP results of Butler and co-workers [15] by describing the reaction mechanisms of peroxynitrite decay and nitration under 15 N-CIDNP conditions. For doing this, N-acetyl-L-tyrosine (Tyrac) is used as an educt instead of L-tyrosine as its solubility in H 2 O is better than that of L-tyrosine [19].…”

“…For explaining these results, it has to be considered that the validity of Scheme 2 has been proven under physiological conditions. Reaction conditions applied during the 15 N-CIDNP experiments -mainly temperature and educt concentrations -are different from those. Therefore, the details of the peroxynitrite decay are more complex than described in Scheme 2.…”

“…A recent kinetic simulation took into account 117 elementary reactions [16]. It seems very likely that, for understanding the 15 N-CIDNP observations, additional reactions have to be taken into account. The purpose of this report is to get a better understanding of the 15 N-CIDNP results of Butler and co-workers [15] by describing the reaction mechanisms of peroxynitrite decay and nitration under 15 N-CIDNP conditions.…”