Bid BH3 (80-99) (acetate) is a biologically active peptide. As a pro-apoptotic member of the BCL-2 protein family’s "only BH3" (BOPS) subset, BID plays a crucial role in the regulation of apoptosis. It is reported that Bid is the first BOP to bind and activate Bcl-2, Bax, and Bak. Acting as a death-inducing ligand, Bid moves from the cytosol to the mitochondrial membrane to deactivate Bcl-2 or activate Bax. When glutamine (Q) or glutamic acid (E) is located at the sequence's N-terminus, they naturally convert to pGlu. The hydrophobic γ-lactam ring of pGlu is thought to enhance peptide stability against gastrointestinal proteases. Consequently, pyroglutamyl peptides are considered a regular subset of such peptides and are included as part of peptide purity in HPLC analysis.