Semaglutide and tirzepatide are the two most-studied incretin-receptor research peptides, and both underlie widely known FDA-approved pharmaceutical brands. This article compares the two molecules on chemistry and receptor pharmacology only.
Brand-name context
Semaglutide is the active molecule in Novo Nordisk's Ozempic and Wegovy. Tirzepatide is the active molecule in Eli Lilly's Mounjaro and Zepbound. All four are registered trademarks of their respective FDA-approved pharmaceutical manufacturers. Research-grade semaglutide and tirzepatide sold for laboratory use are separate products, not manufactured, distributed, tested, or endorsed by Novo Nordisk or Eli Lilly. V8 Peptides has no affiliation, partnership, or commercial relationship with either company or any of the four brands. This article is a chemistry and pharmacology reference for laboratory researchers; it makes no claims about, and does not describe, any pharmaceutical product intended for human use.
Chemical comparison
| Property | Semaglutide | Tirzepatide |
|---|---|---|
| Molecular weight | 4,113.58 Da | 4,813.52 Da |
| Amino acids | 31 | 39 |
| Receptor targets | GLP-1 (single) | GIP + GLP-1 (dual) |
| Fatty acid moiety | C18 diacid | C20 diacid |
| Acylation site | Lys26 | Lys20 |
| DPP-IV resistance | Aib8 | Aib2 |
| Parent hormone backbone | GLP-1 | GIP |
| CAS number | 910463-68-2 | 2023788-19-2 |
Receptor pharmacology
Semaglutide is a single-receptor GLP-1 agonist, useful as a comparator when isolating GLP-1-specific signaling. Tirzepatide's primary sequence derives from native GIP with engineered GLP-1 cross-reactivity, making it a dual-receptor tool compound. Researchers studying combined incretin pathways often pair both alongside triple-agonist retatrutide, which adds glucagon-receptor activity to the GIP/GLP-1 profile.
Analytical differentiation
The ~700 Da molecular-weight difference is readily apparent on ESI-MS. RP-HPLC retention times also differ due to the C18 vs. C20 fatty-acid chain length and differing peptide backbone hydrophobicity. LC-MS/MS peptide mapping after tryptic digestion produces distinct fragment-ion patterns given the different primary sequences (31-residue GLP-1-based vs. 39-residue GIP-based).
Research use only
Both compounds, as sold by V8 Peptides, are intended strictly for laboratory and in-vitro research use by qualified researchers. Neither is for human or animal consumption, and neither is a substitute for, nor equivalent to, any FDA-approved prescription medication. Consult a licensed physician for any question about approved pharmaceutical treatment.