the phosphothreonine residue , which appeared as either an anomalous proline or an unidentifiable phenylthiohydantoin derivative during sequencing , was verified by two-dimensional phosphoamino acid analysis of the phosphopeptides and by resequencing the tryptic peptide after dephosphorylation with exogenous alkaline phosphatase .
C0031684
phosphopeptides
C0030956
peptide