This peptide is histone H4 (1-25) with acetylation at Lys12 and Lys16 and trimethylation at Lys20, followed by a C-terminal GSGS linker and a biotinylated Lys. Trimethylation at Lys20 of histone H4 is catalyzed by Suv4-20 and is involved in transcriptional silencing and heterochromatin formation in eukaryotes. It has been shown that histone H4 is preferentially acetylated first at Lys16, then at Lys12. Diacetylated histone H4 has been shown to bind repressor protein TUP1. Acetylation of histone H4 also regulates heterochromatin formation by promoting the binding of bromodomains to p300 and transcription factor TAFII250 and inhibiting interactions with SIR3. Provided at >95% peptide purity, this peptide was dissolved in distilled water at 1 mg/ml and re-lyophilized to powder form.