The published structure of Eloralintide tells you what the molecule is designed to be. It does not tell you that any particular vial, batch or laboratory sample matches that design. Keeping those two ideas apart is the core of this page.
Eloralintide (LY3841136) is an investigational amylin receptor agonist developed by Eli Lilly and is not approved by any regulator.
Key takeaways
- Eloralintide is a synthetic analogue of human amylin, 37 amino acids long, with three non-coded amino acids at positions 11, 15 and 22.
- Its native disulfide bridge is replaced by a methylene thioacetal bridge, a design change described as improving chemical stability.
- A C20 fatty diacid is attached through a linker at the lysine at position 26. This supports binding to albumin and a long half-life.
- The structure comes from the developer’s own publication. A figure in a paper is a design drawing, not an analysis of a sample.
What the primary paper says
According to PubMed, the 2025 Molecular Metabolism paper by Briere and colleagues (DOI) describes eloralintide as a single fatty acid acylated amylin analogue. The main chain has 37 amino acids, including three non-coded residues at positions 11, 15 and 22. The disulfide bridge found in native amylin is replaced by a methylene thioacetal bridge, which the authors say enhances chemical stability. The main chain is joined to a C20 fatty diacid through a linker at the lysine in position 26, which allows albumin binding as a way to extend half-life for once-weekly administration. The paper reports a terminal half-life of roughly 13 to 15 days in a single-dose human study in healthy adults.
The residue-by-residue drawing is in the paper’s chemical structure figure.
Native amylin and what changed
| Feature | Native human amylin | Eloralintide (as published) |
|---|---|---|
| Length | 37 amino acids | 37 amino acids |
| Ring between two cysteines | Disulfide bridge | Methylene thioacetal bridge |
| Non-natural amino acids | None | Three, at positions 11, 15 and 22 |
| Fatty acid | None | C20 fatty diacid on lysine 26 via a linker |
| Stated purpose of the changes | Not applicable | Stability, once-weekly dosing, reduced immunogenicity risk, amylin receptor selectivity |
The last row reflects the authors’ description of the design aims, not proven outcomes for each change.
Why these modifications matter
The bridge. Disulfide bonds can break or rearrange. A methylene thioacetal bridge keeps the two sulfur atoms linked through a carbon, which is a more robust connection. By simple arithmetic it adds one CH2 unit, about 14 daltons, compared with a disulfide, so a mass measurement can in principle tell the two apart.
The fatty diacid. A fatty chain on lysine 26 lets the peptide bind reversibly to albumin in the blood. Bound drug is cleared more slowly, which is how a weekly schedule becomes possible.
The non-coded residues. Swapping some natural amino acids for non-natural ones is a common way to change stability and receptor behaviour. The paper lists the positions but the effect of each swap is not separately established in the text we reviewed.
Receptor profile. In cell assays the paper reports about 12-fold greater potency at the human AMY1 receptor than at the calcitonin receptor and about 11-fold greater than at AMY3. “Selective” here means preferential, not exclusive, and the authors note there is no agreed threshold for what degree of selectivity matters biologically.
A published structure is not proof of a sample
Four different statements are often blurred together.
- The intended molecule. What the developer designed. Supported by the paper.
- The molecule in the developer’s trial material. Made, tested and controlled by the sponsor under its own specifications. The paper states that eloralintide was synthesised at Eli Lilly by solid-phase methods.
- A sample from another source. Its identity depends on how it was made and tested. No publication describes it.
- A tested sample. A laboratory result applies to the specific sample the laboratory received.
A figure in a paper supports the first statement only. It cannot be used to show that a given sample has the right bridge, the right attachment site or the right sequence.
What a sample-level claim would need
| Claim | Evidence that would support it |
|---|---|
| Right overall composition | Accurate intact mass matching the expected formula, with the calculation shown |
| Right sequence | MS/MS fragments that cover the sequence, with the covered fraction stated |
| Fatty diacid on lysine 26 | Fragment ions localizing the modification to that residue |
| Methylene thioacetal bridge rather than a disulfide or other form | Mass difference plus fragmentation and/or assigned 2D NMR that is consistent with the bridge |
| Correct folding or geometry | Specialized structural analysis, which is rarely done for a research sample |
| Same as the sponsor’s clinical material | Comparison against a reference standard with documented provenance |
Absence of some of these tests is not evidence that a structure is wrong. It means the question has not been answered. Presence of a matching mass does not mean every row has been answered either.
What this page does not establish
- It does not describe how to obtain, prepare or use any material.
- It does not say any commercially circulated material matches the published design.
- It does not claim the bridge or any modification has been confirmed in any specific sample.
Frequently asked questions
What is the Eloralintide sequence? It is a 37-amino-acid analogue of human amylin with three non-coded residues at positions 11, 15 and 22. The residue-by-residue drawing is in the developer’s 2025 paper.
How is Eloralintide different from natural amylin? Per the paper, the disulfide bridge is replaced by a methylene thioacetal bridge, three non-coded amino acids are used, and a C20 fatty diacid is attached at lysine 26.
Why does the bridge matter for testing? It changes the molecule’s mass slightly and its connectivity. Testing that does not examine connectivity may not distinguish the intended bridge from related forms.
Does a matching mass prove the structure? No. It is a necessary check, and it cannot show how atoms are connected.
Does the published structure show a sample is genuine? No. A paper describes the designed molecule. A sample needs its own evidence.
References
- Briere DA, et al. Eloralintide (LY3841136), a novel amylin receptor agonist for the treatment of obesity: from discovery to clinical proof of concept. Molecular Metabolism. 2025;102:102271. DOI 10.1016/j.molmet.2025.102271. PMID 41109426. PMCID PMC12640043.
- Bhattachar SN, et al. Eloralintide, a selective, long-acting amylin receptor agonist for treatment of obesity: Phase 1 proof of concept. Diabetes, Obesity and Metabolism. 2026;28(4):2651-2660. DOI 10.1111/dom.70439. PMID 41559929.
Eloralintide is investigational and not approved. This page is educational information and not medical advice. Last reviewed: October 4, 2026. Published by the EloralintideResearch.com editorial team.
Related reading: Eloralintide CAS number and identifiers