Bioorthogonal labelling of 3-nitrotyrosine in peptides and proteins through diazotisation mediated azidation

A new chemical derivatisation method to functionalise peptide and protein bound 3-nitrotyrosine residues is described. By transforming 3-nitrotyrosine to 3-azidotyrosine, the method enables 'click chemistry'-based labelling of the 3-nitrotyrosine residues and provides new opportunities for the study of this post-translational modification in biological samples.