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Molecular Weight
Purity
Storage
Appearance
Solubility
01
Tirzepatide is a synthetic 39-residue peptide that activates two incretin receptors: the GIP receptor and the GLP-1 receptor. Its backbone is based on the GIP sequence, with changes that add GLP-1 receptor activity, and it carries a C20 fatty diacid on Lys20 that enables albumin binding.
As a dual agonist, it sits between the selective GLP-1 receptor agonist semaglutide and the triple agonist retatrutide, and is widely used as the dual-receptor reference in incretin research. It is supplied as a lyophilized reference material for in vitro receptor pharmacology and for analytical work on lipidated peptides.
02
Tirzepatide combines a GIP-like backbone with non-standard residues and a lipid side chain.
Tyr1 N-terminus
Like native GIP, the sequence starts with tyrosine rather than the histidine of GLP-1.
Aib2 and Aib13
α-Aminoisobutyric acid at position 2 blocks DPP-IV cleavage; a second Aib at position 13 adds backbone rigidity and protease resistance.
Lipidated Lys20
The side-chain amine of Lys20 carries eicosanedioic acid (C20 diacid) linked through γ-glutamic acid and two AEEA (8-amino-3,6-dioxaoctanoic acid, also called OEG) units. Semaglutide uses the same type of γGlu–2×AEEA linker with a shorter C18 diacid.
C-terminal extension
The sequence ends in Gly-Gly-Pro-Ser-Ser-Gly-Ala-Pro-Pro-Pro-Ser-NH₂, a proline-rich, exendin-4-like tail, with an amidated C-terminus.
Sensitive residues
Trp25 is the main photo-oxidation site, and Gln19 and Gln24 can deamidate. There is no methionine or cysteine.
03
In vitro, tirzepatide is characterised by measuring its activity at each receptor separately.
Dual-receptor potency
cAMP assays in GIP receptor- and GLP-1 receptor-expressing cells give concentration–response curves at each target. Published data describe an imbalanced profile, with potency at the GIP receptor comparable to native GIP and lower relative potency at the GLP-1 receptor.
Signalling bias
Pathway-selective assays have reported that at the GLP-1 receptor, tirzepatide favours cAMP signalling over β-arrestin recruitment compared with native GLP-1, a form of biased agonism that is an active research topic.
Comparative profiling
Run alongside semaglutide (GLP-1R selective) and retatrutide (GIP/GLP-1/glucagon) to rank potency and selectivity across the incretin receptors. As with all lipidated peptides, results depend on albumin content in the assay.
All observations described here come from cell-free and cell-based in vitro systems.
04
Dual-agonist reference
The standard GIP/GLP-1 dual agonist in receptor panels comparing single, dual and triple agonists.
Lipidated peptide HPLC
A test compound for reversed-phase methods for acylated peptides, and a direct comparison to semaglutide for the effect of a C20 versus C18 diacid.
Linker and lipid analysis
Used to develop LC-MS/MS methods that confirm the Lys20 attachment site and the full diacid–γGlu–2×AEEA side chain.
Self-association studies
The amphiphilic lipid side chain can promote self-association; dynamic light scattering and size-exclusion chromatography are used to study this.
05
Storage
Store the lyophilized powder at −20 °C, sealed, desiccated and protected from light. Let the vial reach room temperature before opening.
Solubility and pH
Like semaglutide and retatrutide, tirzepatide is least soluble in the mildly acidic range near its isoelectric point. Neutral to slightly basic buffers, or DMSO for stock solutions, dissolve it more reliably.
Light sensitivity
Trp25 can photo-oxidise to kynurenine-type products. Use amber or foil-wrapped containers.
Aggregation
Prepare concentrated stocks carefully and check for self-association (for example by size-exclusion chromatography) when working at higher concentrations.
Solutions and labware
Use low-binding polypropylene tubes, freeze single-use aliquots and avoid repeated freeze–thaw cycles. Strongly acidic or basic conditions can slowly hydrolyse the linker amide bonds.
06
Analysis must confirm the peptide sequence, the non-standard residues and the full lipid side chain.
HPLC
Wide-pore (300 Å) C4 or C8 columns at elevated temperature usually give the best peak shape and recovery. Retention differs from semaglutide because of the longer C20 diacid and the different backbone; exact conditions are set during method development.
Mass spectrometry
ESI-MS in positive mode shows charge states around +4 to +7; deconvolution should give about 4813.5 Da. Use formic acid rather than TFA for LC-MS.
Side-chain confirmation
Digestion followed by LC-MS/MS of the fragment containing Lys20 confirms the attachment site, the C20 diacid, the γ-glutamate and both AEEA units. Fragments lacking one or more linker components identify incomplete or degraded side chains.
Impurity profile
Typical checks include the des-lipid peptide, partially linked side chains, Trp25 oxidation (+16, +32 Da), glutamine deamidation (+1 Da), truncated sequences and the free-acid C-terminus.
07
The γ-glutamate and two AEEA (OEG) units connect the C20 diacid to Lys20. They space the lipid away from the peptide backbone and add some hydrophilicity, helping the lipid bind albumin without interfering with receptor binding. Semaglutide uses the same type of linker with a C18 diacid.
Not as a long ladder. A 44 Da spacing is typical of polyethylene glycol chains, but tirzepatide’s linker contains only two short AEEA units. The linker is better confirmed by the specific masses of fragments that contain or have lost the AEEA, γ-glutamate and diacid components.
Published in vitro work reports that at the GLP-1 receptor it favours cAMP signalling over β-arrestin recruitment compared with native GLP-1. Its overall profile is also imbalanced, with relatively stronger activity at the GIP receptor.
It has a longer C20 diacid and a different peptide backbone, so its retention and peak shape differ under the same conditions. Both are best analysed on wide-pore C4 or C8 columns at elevated temperature, with the separation optimised during method development.
A combination of enzymes, typically trypsin together with Glu-C or chymotrypsin, analysed by LC-MS/MS. Overlapping fragments cover the Aib residues at positions 2 and 13 and the lipidated Lys20, which trypsin does not cleave after.
Avoid the mildly acidic range near its isoelectric point, where solubility is lowest. Neutral to slightly basic buffers, or DMSO for stock solutions, work better.
This material is not. Although tirzepatide is the active ingredient of approved medicines, the material listed here is supplied strictly as a reference compound for laboratory and analytical research and is not for human or animal use.
Tirzepatide Research Reference. (2026). Pure Peptides Labs Research Catalogue. Retrieved from https://purepeptideslabs.net/research-catalogue/metabolic-research-peptides/tirzepatide/
Materials listed on this platform are supported by independent testing and published documentation for laboratory research contexts.
