Notes: Nitrotyrosine (Item No. 89540) is formed by peroxynitrite-mediated nitration of protein tyrosine residues. Its presence on proteins can be used as a marker for peroxynitrite formation in vivo.{5439,1269,4663,5357} Nitrotyrosine AChE Tracer is a conjugate formed between nitrotyrosine and acetylcholinesterase (AChE). It is used in competitive ELISAs designed to quantify nitrotyrosine.