Mass spectra of tryptic peptides of nitrated ERK1.

<p>Tryptic peptides of nitrated recombinant ERK1 were immunoprecipitated with anti-nitrotyrosine antibodies. <b><i>A</i></b>: Mass spectrum (500–3000 Da) shows a major peak with a monoisotopic mass of 1552.91 corresponding to GLKY¹⁵⁶-(NO2)IHSANVHR. <b><i>B</i></b>: Detailed spectrum (2742–2755.5 Da) shows a major peak with a monoisotopic mass of 2749.28 corresponding to the peptide ASTLEAMRDVYIVQDLMETDLYK containing one nitrated Tyr, Tyr¹¹⁹ or Tyr¹³⁰. Other peaks correspond to peptides which do not contain Tyr and were adsorbed non-specifically to the anti-nitrotyrosine agarose beads.