FIGURE 2.

Assignment of modification sites by MALDI-TOF/TOF laser-induced dissociation fragmentation of hydroxylated peptide substrates. Modification sites were confirmed by enzymatic hydroxylation of synthetic peptide substrates followed by MS/MS analysis with MALDI-TOF/TOF laser-induced dissociation. A, CODD HIF-2α. B, NODD HIF-2α. C, NODD HIF-1α. D, tankyrase-1 (35-mer). Assay conditions were as follows. 4–5 μm enzyme, 100 μm peptide, 50 μm Fe(II), 300 μm 2OG, 1 mm l-ascorbate in HEPES 50 mm (pH 7.5) were incubated at 37 °C at atmospheric O₂ for 20 min.