BioMed Research International / 2010 / Article / Fig 7

Methodology Report

Enhanced MALDI-TOF MS Analysis of Phosphopeptides Using an Optimized DHAP/DAHC Matrix

Figure 7

The MALDI MS analysis of phosphopeptides from CDK1-treated human histone H1. MS spectra of the tryptic peptides from CDK1-treated histone H1 with the untreated (Figure 7( a )) and alkaline phosphatase-treated histone H1 (Figure 7( b )). The two panels on the right show the magnified spectra to indicate the two phosphopeptides labeled with asterisks ( ∗ ). The MALDI-TOF/TOF-MS analysis of phosphorylation sites on the two monophosphopeptides VApTPKKASKPK, m/z 1234.7 (c), APTKKPKApTPVKK, m/z 1473.9 (d) from the CDK1-treated human histone H1. The neutral-loss peak of phosphopeptide was noted as [MH- H 3 P O 4 ] + . The fragment patterns of peptides were shown in the magnified MS/MS spectra. “B” in the amino sequence indicates a dehydroamino-2-butyric acid residue converted from a phosphothreonine residue by beta-elimination of H 3 P O 4 . All the spectra were detected using DHAP/DAHC matrix in the positive mode.
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