Tirzepatide is a 39-amino-acid dual GIP/GLP-1 receptor agonist, structurally based on the native GIP hormone with engineered cross-reactivity for the GLP-1 receptor. It is the active molecule behind Eli Lilly's FDA-approved pharmaceutical products.
Brand-name context
Mounjaro and Zepbound are registered trademarks of Eli Lilly and Company, referring exclusively to their FDA-approved, prescription pharmaceutical formulations of tirzepatide (Mounjaro for type 2 diabetes, Zepbound for chronic weight management and obstructive sleep apnea). Research-grade tirzepatide sold for laboratory use is a separate class of product — it is not manufactured, distributed, tested, or endorsed by Eli Lilly, and V8 Peptides has no affiliation, partnership, or commercial relationship with Eli Lilly or either brand. This article discusses tirzepatide strictly as a research compound; it does not describe or compare pharmaceutical products intended for human use.
Molecular identity
Tirzepatide has a molecular weight of approximately 4,813.52 Da and the molecular formula C225H348N48O68. Its 39-residue backbone is based on native GIP, with an Aib2 substitution for DPP-IV resistance and a C20 fatty-diacid conjugated at Lys20 via a gamma-glutamyl/mini-PEG linker. CAS number: 2023788-19-2. The ~700 Da mass difference relative to semaglutide and the distinct dual-receptor design make the two peptides straightforward to distinguish analytically.
Dual-receptor design
Tirzepatide's primary sequence gives it high native affinity for the GIP receptor, while engineered mid-chain substitutions confer meaningful cross-reactivity with the GLP-1 receptor — distinct from co-administering two separate single-receptor peptides. This dual-agonist architecture makes tirzepatide a useful reference compound when studying combined incretin-receptor signaling, alongside triple agonists such as retatrutide, which adds glucagon-receptor activity on the same GIP-based backbone.
Analytical characterization
Research-grade tirzepatide identity and purity are typically confirmed by reversed-phase HPLC (≥95% purity target) and ESI mass spectrometry (expected [M+H]+ consistent with a monoisotopic mass near 4,813.5 Da), with LC-MS/MS peptide mapping used to confirm the Lys20 acylation site. As with all research peptides, reproducibility depends on documented identity and purity — see third-party testing explained.
Research use only
Tirzepatide sold by V8 Peptides is intended strictly for laboratory and in-vitro research use by qualified researchers. It is not for human or animal consumption, and is not a substitute for, nor equivalent to, any FDA-approved prescription medication. Consult a licensed physician for any question about approved pharmaceutical treatment.