| Bombesin [Leu-(R)-Leu4], also known as [Leu-psi(CH2NH)Leu4]bombesin or by its pseudo-peptide modification (reduced peptide bond), is a well-characterized, potent bombesin receptor antagonist. It is commonly used in research to block the action of bombesin-like peptides, such as gastrin-releasing peptide (GRP). Key Characteristics and Function Molecular Mechanism: Acts as a specific and competitive antagonist at the receptor level. Specifically, it contains a reduced peptide bond (represented by psi) between the Leucine at position 13 and the Leucine at position 14, which prevents the biological activation of the receptor upon binding. Biological Effects:Inhibition of Mitogenesis: Bocks the growth-promoting (mitogenic) effects of bombesin-like peptides in various cell lines, such as Swiss 3T3 cells.Signaling Blockade: It inhibits bombesin-stimulated mobilization of intracellular calcium (\(Ca {2+}\)), activation of protein kinase C, and activation of the MAP kinase pathway. Competitive Binding: Effectively displaces labeled ligands like \({} {125}I\)-Gastrin-Releasing Peptide (GRP) from bombesin receptors (specifically the BB2 subtype). Scientific Applications Cancer Research: Because bombesin-like peptides (such as GRP) function as autocrine growth factors in several human cancers, including small-cell lung cancer (SCLC), this antagonist is used as a tool to study anti-tumor strategies.Structural Studies: It serves as a probe for investigating the molecular structure of bombesin and the requirements for receptor-ligand interactions. Source: Synthetic peptide Purity: 95% (HPLC, Mass Spec) Appewarance: White to off-white lyophilized powder Sequence: Pyr-Gln-Arg-Leu-Gly-Asn-Gln-Trp-Ala-Val-Gly-His-Leu-psi(CH2NH)-Leu-NH2 (modification at the C-terminus). Sequence (linear): Pyr-Gln-Arg-Leu-Gly-Asn-Gln-Trp-Ala-Val-Gly-His-Leu-(R)-Leu-NH2 Storage and Stability: Lyophilized powder may be stored at 4C for short-term only. Stable for 12 months at -20C after receipt. Reconstitute to nominal volume (see reconstitution instructions for peptides) and store at -20C. For maximum recovery of product, centrifuge the original vial prior to removing the cap. Further dilutions can be made in assay buffer. |
