Figure 5. Mass spectra of identified endogenous peptides with serine and threonine acetylation and their synthetic counterparts.

Major peaks are labelled in the mass spectra and the fragment ions indicated in the peptide sequence using standard Mascot nomenclature [56]. A) A novel site of serine acetylation on residue S35 of H1. B) A novel site of threonine acetylation on residue T80 of H3. The reporter ion characteristic of the loss of an acetyl group (−80 Da) from the parent ion is indicated. C) A novel site of serine acetylation on S112 histone H1.