Bradykinin is a nine-amino-acid peptide studied in laboratory research as the reference agonist for the bradykinin B2 receptor and, through its metabolites, a tool for studying the inducible B1 receptor in vitro. Both receptors are class A G protein-coupled receptors, and bradykinin is widely used in cell-based assays as a well-characterized signaling stimulus.

Structure: bradykinin has the sequence Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg. It is generated in biological systems by proteolytic processing of kininogen precursors, and in the laboratory it is supplied as a defined synthetic peptide. Its rapid enzymatic degradation — cleavage by peptidases such as angiotensin-converting enzyme and carboxypeptidases, producing fragments including des-Arg9-bradykinin — is itself a subject of laboratory study and a key handling consideration. Identity and purity are confirmed by HPLC and mass spectrometry, and the lot-matched COA is reviewed before use.

Laboratory applications: cell culture assays measuring B2 receptor signaling (calcium mobilization, inositol phosphate accumulation, and downstream kinase readouts), comparative studies of bradykinin fragments and metabolites at B1 versus B2 receptors, peptidase stability studies in defined buffer and serum-containing systems, and use as a reference agonist with selective antagonist controls. Vehicle controls, analytical verification, and replication are standard. In vitro findings describe receptor and enzyme behavior in laboratory systems only; no conclusions about human use can be drawn from them.

Analytical notes: store lyophilized material sealed, protected from light and moisture; verify identity and purity by HPLC/MS on receipt; because of its short peptidase half-life in biological matrices, note preparation time and conditions in laboratory records; avoid repeated freeze-thaw cycles.

Disclaimer: This material is supplied for laboratory research purposes only. Not for human consumption. Not for medical, therapeutic, diagnostic, or veterinary use. No dosing, reconstitution-for-use, or efficacy information is provided or implied.

Citations: Marceau F & Regoli D, Bradykinin receptor ligands reviews; Leeb-Lundberg LMF et al., International Union of Pharmacology kinin receptor classification, Pharmacological Reviews (2005); standard HPLC/MS peptide characterization methods.