Figure 3.
MALDI mass spectrometry confirms the incorporation of ADP-ribose in peptide substrates. (A) Peptides P12 and P39 were ADP-ribosylated in a non-radioactive assay. The treated peptides were analyzed by MALDI mass spectrometry. Samples treated with TbSIR2 show mass changes of 540 Daltons, consistent with the addition ADP-ribose moieties to the peptides. (B) MALDI mass spectrometry analysis of the ADP-ribosylation of peptide P12pR. The reactions were carried out using 20 μM peptide with 100 μM NAD+. Detection of the ADP-ribosylated P12pR was improved using higher concentrations of peptide and NAD+.