Development of a label-free, quantitative mass spectrometry-based deacylation assay.

<p>(<b>A</b>) Different amounts of acetylated (○) and deacetylated (•) CPS1-Lys527 peptide are plotted against their respective mass spectrometry signal areas. Interpolations (lines) show the linear correlations between peptide amounts and detected signals, and the slightly different slopes for the two peptide species. (<b>B</b>) Ratios of the injected amounts of deacetylated and acetylated peptide plotted against ratios of the measured log₁₀ signal areas (•). Equation and correlation for the linear interpolation (line) are indicated. (<b>C</b>) Scheme for the mass spectrometry-based deacylation assay. Percent deacetylation is calculated by normalizing the product area to the total signal area, and deacetylation rates are determined through analysis of aliquots taken after different incubation times.