Figure 1.

Overall experimental workflow as illustrated by the identification of H4 (P62805) isoform S1acK8acK12acK20me2. (a) UV chromatogram from first dimension RPLC separation of 7.5 μg of HeLa core histone mixture. (b) MS-only total ion current (TIC) chromatogram from WCX-HILIC-MS/MS analysis of H4 fraction from the first dimension. (c) Representative mass spectrum (only charge state 13 shown) at retention time 136.54 min from WCX-HILIC-MS/MS analysis of H4 fraction from the first dimension. (d) Representative deconvoluted CID spectrum for precursor ion m/z 877.12 with matching fragments marked with 'triangles'. The inset is the matching fragment mapping on the protein amino acid sequence with PTMs color-coded. CID, collision induced dissociation; PTMS, post-translation modifications; RPLC, reversed phase liquid chromatography; WCX-HILIC-MS/MS, weak cation exchange-hydrophilic interaction liquid chromatography-tandem mass spectrometry.