Figure 3.

The ADPr—peptide bond is hydrolyzed under mild conditions. (a) Synthesized ADPr—P14p6 peptide was equilibrated at 37 °C and pH 6.0 (blue), pH 7.0 (purple), or pH 8.0 (green) and ADPr hydrolysis was monitored at the indicated times using TLC-MALDI. The unmodified and modified peaks are shown for comparison. (b) MS spectra were integrated to determine the relative levels of ADPr hydrolysis and fit to a pseudo first-order rate expression to determine the half-life of the ADPr modification (mean ± S.E.M., n = 3). (c) Incubation at room temperature stabilizes the ADPr—peptide bond. Experiments were performed as in (a) at 25 °C. (d) Determination of ADPr half-lives at 25 °C. (e) Incubation on ice effectively halts ADPr hydrolysis in mild acid. Experiments were performed as in (a) at 4 °C. (f) Determination of ADPr half-lives at 4 °C.