This peptide is Histone H3 amino acid residues 73 to 83 tri-methylated at Lysine 79. Histone lysine methylation plays a role in transcriptional regulation. H3K79 can be methylated by Dot1 methyltransferase.
Pyroglutamyl (pGlu) peptides may spontaneously form when either Glutamine (Q) or Glutamic acid (E) is located at the sequence N-terminus. The conversion of Q or E to pGlu is a natural occurrence and in general it is believed that the hydrophobic γ-lactam ring of pGlu may play a role in peptide stability against gastrointestinal proteases. Pyroglutamyl peptides are therefore considered a normal subset of such peptides and are included as part of the peptide purity during HPLC analysis.