Quick answer
Semaglutide is a 31-residue GLP-1 receptor agonist analog: native GLP-1(7-37) with two amino acid changes and a C18 fatty-diacid side chain on lysine-26, which binds albumin and extends the half-life to about a week. Ozempic and Wegovy are Novo Nordisk trademarks for its approved pharmaceutical products, which are separate from laboratory research material.
- Formula and mass: C187H291N45O59, about 4,113.6 Da; CAS 910463-68-2
- Stabilization: Aib at position 8 (DPP-IV resistance), Arg at position 34, γGlu-2×OEG linked C18 diacid at Lys26
- Verification: RP-HPLC purity plus ESI mass spectrometry; see semaglutide purity testing
- V8 listing: semaglutide research vial, 10 mg lyophilized powder, ≥98% HPLC purity specification
- Affiliation: V8 Peptides has no relationship with Novo Nordisk or either brand
Research Use Only. For laboratory research use only; not for human consumption.
Brand names versus the molecule
Ozempic and Wegovy are registered trademarks of Novo Nordisk A/S. They refer exclusively to that company's FDA-approved pharmaceutical formulations of semaglutide, the first marketed for type 2 diabetes and the second for chronic weight management. Research-grade semaglutide sold for laboratory use is a separate class of product: it is not manufactured, distributed, tested or endorsed by Novo Nordisk, and V8 Peptides has no affiliation, partnership or commercial relationship with Novo Nordisk or either brand. This article discusses semaglutide strictly as a research compound and does not describe or compare pharmaceutical products. The research context is in the semaglutide research overview and what is semaglutide.
The useful distinction for a laboratory is between a name and a specification. A brand name identifies a finished, regulated product. A research buyer needs the opposite: the chemical identity of the molecule, defined by sequence, formula and mass, and a lot-specific analytical record showing the material in the vial matches it.
| Item | Semaglutide as a research compound |
|---|---|
| Class | Acylated GLP-1 receptor agonist analog |
| Backbone | GLP-1(7-37) numbering, 31 residues |
| Molecular formula | C187H291N45O59 |
| Average molecular weight | About 4,113.6 Da |
| CAS number | 910463-68-2 |
| Supplied form (V8) | Lyophilized powder, 10 mg vial |
Molecular identity
The backbone follows the native GLP-1(7-37) sequence with three deliberate features that together define the molecule.
- Aib at position 8. The native alanine is replaced by α-aminoisobutyric acid, a non-natural residue that blocks cleavage by dipeptidyl peptidase-IV, the enzyme that destroys native GLP-1 within minutes.
- Arg at position 34. Lysine-34 is replaced by arginine, leaving a single lysine (position 26) available for the lipid attachment.
- C18 diacid on Lys26. An octadecanedioic acid chain is attached through a γ-glutamic acid and two mini-PEG (OEG) spacer units.
The fatty-diacid moiety binds serum albumin reversibly, which shields the peptide from degradation and renal clearance. This is a stabilization strategy shared with tirzepatide, which uses an analogous but chemically distinct C20 diacid at Lys20; the comparison is laid out in semaglutide vs. tirzepatide: brand chemistry and tirzepatide brand chemistry.
Design and receptor pharmacology
As a single-receptor GLP-1 agonist, semaglutide is used as a comparator against dual and triple agonists such as tirzepatide and retatrutide, letting researchers separate GLP-1-receptor-specific signaling from GIP- or glucagon-receptor contributions. The incretin receptors themselves are covered in incretin receptors explained, and the wider class in GLP-1 receptor agonists in research.
The extended half-life of about seven days, against roughly two minutes for native GLP-1, results from albumin binding mediated by the fatty-diacid moiety together with the DPP-IV-resistant Aib substitution. The design pattern, resistance to proteolysis plus reversible protein binding, recurs across long-acting incretin-class research peptides.
| Feature | Native GLP-1 | Semaglutide |
|---|---|---|
| Position 8 | Alanine | Aib |
| Position 34 | Lysine | Arginine |
| Lipidation | None | C18 diacid at Lys26 via γGlu and OEG linker |
| Approximate half-life | About 2 minutes | About 1 week |
Analytical characterization
Research-grade semaglutide identity and purity are typically confirmed by reversed-phase HPLC (≥98% purity target) and ESI mass spectrometry, with the deconvoluted mass consistent with the theoretical value near 4,113 Da. The principles are covered in HPLC vs. mass spectrometry; the molecule-specific points are in semaglutide purity testing.
Impurities specific to a lipidated peptide
- Unacylated peptide: backbone lacking the lipid side chain, which is substantially lighter and elutes much earlier on reversed-phase columns
- Mis-acylated or over-acylated forms: lipid attached at the wrong site or in duplicate
- Oxidation (+16 Da) of the tryptophan side chain and deamidation (about +1 Da)
- Truncated and deleted sequences from incomplete couplings across a 31-residue chain
The lipid chain makes semaglutide considerably more hydrophobic than its peptide backbone alone, so retention behavior on a C18 column differs from unmodified peptides, and a method developed for short unmodified peptides will not necessarily suit it.
What the V8 listing states
The semaglutide research vial page lists a 10 mg lyophilized powder with a ≥98% HPLC purity specification and the molecular formula above, with storage at 2–8 °C and −20 °C for long-term holds, protected from heat, moisture and light. Lot-level analytical reports, where published, are collected in the CoA library; the sequence and identity field on the page directs readers to the certificate rather than restating it. Concentration planning (mg of peptide divided by mL of solvent) can be done in the reconstitution calculator, and handling is covered in semaglutide reconstitution and handling and semaglutide storage and stability.
Handling a lipidated peptide in the lab
Lipidation changes bench behavior as well as chemistry. The fatty-diacid chain makes semaglutide more prone to adsorb to plastic and glass surfaces at low concentration than an unmodified peptide, and more prone to aggregation if the solution is agitated hard or taken to extreme pH. Common precautions in research handling include low-bind labware, gentle swirling in place of vigorous vortexing, and preparing working dilutions from a defined stock (mg of peptide divided by mL of solvent) rather than from repeated serial dilutions of very dilute solutions. Because the albumin-binding property is a defining feature, assay buffers that contain serum albumin will change the apparent free concentration of the compound, which matters when comparing receptor-assay results between laboratories that use different media.
Dry lyophilized powder is the most stable form. Once dissolved, the material is more exposed to hydrolysis, oxidation and adsorption, which is why recording the reconstitution date and avoiding repeated freeze-thaw cycles are routine practices; see semaglutide storage and stability.
Why a brand-chemistry distinction matters for researchers
Three practical reasons to keep the research compound and the branded products distinct:
- Documentation. A research lot is characterized by its own certificate. Nothing about a branded product's regulatory documentation transfers to it.
- Claims discipline. Results from cell or receptor-assay work should be reported as work on a defined research compound, with its lot analytics cited, not as a statement about a marketed product.
- Reproducibility. Citing the molecular identity (sequence, modification, mass) lets other laboratories reproduce the material, which a brand name does not.
For sourcing considerations, see where to buy semaglutide for research and the semaglutide and tirzepatide buyer's guide.
Summary of the chemistry
Put briefly: semaglutide is native GLP-1(7-37) hardened against enzymatic cleavage (Aib8), simplified to one lysine (Arg34), and equipped with a C18 diacid albumin-binding tail at Lys26. Those three modifications explain its mass, its week-long half-life, its hydrophobic chromatographic behavior and the specific impurities an analyst looks for. Everything else on a research label, including the brand-name associations, is outside that chemical definition.
Research use only
Semaglutide sold by V8 Peptides is intended strictly for laboratory and in-vitro research by qualified researchers. It is not for human or animal consumption and is not a substitute for, or equivalent to, any FDA-approved pharmaceutical product. Questions about approved pharmaceutical products should be directed to a licensed physician.
Frequently asked questions
Is research semaglutide the same as Ozempic or Wegovy?
No. Those are Novo Nordisk's trademarked, regulated pharmaceutical products. Research semaglutide is a laboratory compound supplied with its own analytical documentation and no connection to Novo Nordisk.
Does V8 Peptides have any affiliation with Novo Nordisk?
No. V8 Peptides has no affiliation, partnership or commercial relationship with Novo Nordisk or with the Ozempic and Wegovy brands.
What is the molecular weight of semaglutide?
About 4,113.6 Da, with molecular formula C187H291N45O59. The CAS number is 910463-68-2.
Why does semaglutide last longer than native GLP-1?
Two features: the Aib substitution at position 8 resists DPP-IV cleavage, and the C18 diacid side chain binds albumin. Together they extend the half-life from about two minutes to about a week.
How does semaglutide differ from tirzepatide structurally?
Semaglutide is a 31-residue single-receptor GLP-1 agonist with a C18 diacid on Lys26. Tirzepatide is a 39-residue dual GIP/GLP-1 agonist with a C20 diacid on Lys20.
How is research semaglutide verified?
By reversed-phase HPLC for purity and ESI mass spectrometry for identity, reported on a lot-specific certificate. Lipidation-specific impurities such as unacylated peptide are part of what the analysis looks for.
What does V8 list for semaglutide?
A 10 mg lyophilized vial with a ≥98% HPLC purity specification, on the product page. Lot reports are in the CoA library as published.
Research Use Only. For laboratory research use only; not for human consumption. Supplied strictly for laboratory research and development. This article is research education, not usage guidance.
References
- V8 Peptides. Semaglutide research overview.
- V8 Peptides. Semaglutide purity testing.
- V8 Peptides. Semaglutide vs. tirzepatide: brand chemistry comparison.
- V8 Peptides. HPLC vs. mass spectrometry.
- V8 Peptides. Semaglutide research vial.