This is a PUMA (p53 upregulated modulator of apoptosis) BH3 domain peptide. PUMA together with Bcl-xL, and cytoplasmic p53 coordinates p53 functions. PUMA proteins bind Bcl-2, localize to the mitochondria, and induce cytochrome C release and apoptosis in response to p53. PUMA may be a direct mediator of p53-induced apoptosis.
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.