Figure 11.

Affi-BAMS assay for H3 (K9-acetylation) in U2OS cells upon SAHA treatment. MALDI MS spectra from an Affi-BAMS assay for H3 (K9-acetylation) in U2OS cells upon DMSO control (A, Top) and 5 µM SAHA treatment for 24h (B, bottom). The spectra were normalized against a common H3 derived peptide (MH⁺ = 1700.398 [blue circle]) and overlaid in mMass to reflect the relative abundance. Delta change of 14, 42 and 80 m/z are observed accounted by the hyper modified regions within H3 (methylation, acetylation and phosphorylation). There is an increase in overall signal compared to the control as well as a shift in higher molecular weight species suggesting an increase in cross talk of PTMs as well as higher order acetylation. An MS/MS was obtained and searched through Protein Prospector to identify two peaks (1740.97 [black triangle] and 1984.28 [red triangle] m/z). The following peptides from H3 were identified: QTARK(Acetyl)STGGK(Acetyl)APRK(Acetyl)Q and TK(Methyl)QTARK(Acetyl)STGGK(Acetyl)APRK(Acetyl)Q, respectively.