Semaglutide: A Research Primer

Semaglutide is a synthetic peptide analog of human GLP-1(7-37), built on that 31-residue backbone with a fatty-acid side chain anchored to a single lysine. It belongs to the class of long-acting GLP-1 receptor agonists and appears in metabolic-science research under CAS number 910463-68-2.

What semaglutide is

Semaglutide is a fully synthetic peptide, assembled residue by residue rather than pulled from tissue.

Its starting point is glucagon-like peptide-1, a peptide the body makes on its own. The relevant stretch is the 7-37 fragment, and semaglutide is that fragment with three deliberate changes. Position 8 carries Aib, 2-aminoisobutyric acid, in place of the native alanine. Position 34 carries arginine where the native sequence has lysine. The lysine at position 26 anchors a long lipid side chain. The word analog is doing real work in the name here: this is the natural sequence altered at specific points, not the natural peptide.

That lipid side chain is what puts semaglutide in the long-acting subgroup rather than among the plain GLP-1 fragments. Structurally it is a C18 diacid tethered to the peptide through a short linker, and it is the single feature that most sets the molecule apart from the backbone it is based on. Those three edits are also what separate it on paper from other GLP-1(7-37) analogs, which share the same backbone but differ in exactly which positions are swapped and what kind of side chain, if any, is attached.

The chemistry

The identity data does not change between suppliers, so it is the first thing to verify on any label or certificate.

• CAS number: 910463-68-2
• Molecular formula: C187H291N45O59
• Molecular weight: approximately 4113.6 g/mol
• Class: long-acting GLP-1 receptor agonist analog
• Backbone: GLP-1(7-37), 31 residues
• Backbone sequence: His-Aib-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe-Ile-Ala-Trp-Leu-Val-Arg-Gly-Arg-Gly
• Modifications: Aib at position 8, Arg at position 34
• Side chain: a C18 diacid (octadecanedioic acid) at Lys26, linked through a gamma-glutamate and two short PEG-like spacers

The molecular formula counts the full modified peptide, side chain included. A quick lookup of the bare GLP-1(7-37) backbone, with no substitutions and no lipid, returns a lower mass, so when you cross-check a mass-spec figure against a certificate, compare it against the modified molecule and not the native fragment. Mixing up the two is an easy way to talk yourself into thinking a correct number looks wrong. The CAS number settles it faster than any name, because a name can be transcribed a dozen ways and a registry number cannot.

Where it appears in the research literature

In the published literature, semaglutide sits in metabolic science.

That is the field where the compound and its CAS number are cited. For the primary sources themselves, search on the CAS number, the term semaglutide, and the GLP-1(7-37) analog description rather than trade names, which scatter across patents and regulatory filings. The identifiers matter more than the labels here, since the same molecule travels through the literature under several names and development codes.

How it is supplied and handled

It is supplied as a lyophilized solid, kept cold, sealed, and out of light.

Semaglutide ships freeze-dried. Store it at -20C, keep it in a light-tight container, and leave the vial sealed until you are working with it. As with most lyophilized peptides, there may be a bulking agent in the vial so the cake is visible and easy to handle, and a good certificate accounts for that filler when it reports mass. Everything here is about keeping the dry solid intact: a steady low temperature, protection from light and moisture, and an unbroken seal. The current listing is on [the semaglutide product page](/products/semaglutide).

How the lots are tested

Two tests carry the weight: identity and purity.

Purity is measured by HPLC read at 220 nm, the wavelength peptide bonds absorb at, which is how the target peptide gets separated from related impurities on the readout. Identity is confirmed by mass spectrometry, the measurement that checks the molecule matches the label rather than only checking how clean the sample is. Kits Peptides third-party tests each lot it stocks at an independent third-party laboratory.

If you have not worked through one of these reports before, there is a walkthrough on [how to read a peptide COA](/research/how-to-read-a-peptide-coa) built around two real certificates, plus a broader [checklist for buying research peptides in Canada](/research/buying-research-peptides-canada) covering what else to confirm before you order. Kits Peptides ships tracked from Vancouver, BC across Canada.

*All products are supplied as laboratory reagents for research use only. Not for human or veterinary use.*