Epitalon Chemistry: Ala-Glu-Asp-Gly Tetrapeptide
A bench-level reference sheet on Epitalon, the short linear tetrapeptide Ala-Glu-Asp-Gly: how a compact acidic four-residue sequence is assembled, how its identity is confirmed, and what to read off it before keeping one as a research reference standard.
Sequence and Structure
Epitalon is a short linear tetrapeptide, a four-residue chain with the sequence Ala-Glu-Asp-Gly, written in single-letter code as AEDG. It is short even by the standards of research peptides, and its character comes less from its length than from its composition: two of its four residues, glutamate and aspartate, carry acidic carboxyl side chains, which gives the whole peptide a distinctly acidic profile.
Because the glutamate and aspartate side chains are deprotonated across most of the working pH range, the peptide carries net negative charge in solution, balanced only by the small neutral alanine and glycine residues at the ends. The result is a compact, highly water-soluble molecule with no internal disulfides, no cyclization, and no terminal modification to manage. For a research chemist the practical takeaway is that almost everything that follows, from solubility to chromatographic behavior to handling, traces back to this small acidic four-residue arrangement.
Origin and Family: A Short Linear Peptide
Epitalon is grouped with the short linear research peptides and is catalogued under the Other Compounds class, a bucket that collects well-defined sequences which do not fall into the receptor-analog, copper-complex, or growth-factor families. It is sometimes written Epithalon or referred to by its tetrapeptide sequence AEDG, but all of those labels point to the same simple Ala-Glu-Asp-Gly chain.
What sets a peptide like this apart from most of the catalog is its plainness. There is no cyclization, no fatty-acid lipidation, no metal coordination, and no non-standard residue to account for during the build. That makes Epitalon a clean reference point: a compact acidic sequence that behaves predictably under synthesis and analysis, which is why it sits comfortably next to other short peptides such as the SS-31 tetrapeptide in the reference catalog.
Why Fmoc Synthesis Suits a Short Acidic Tetrapeptide
At four residues, Epitalon is well within the comfortable range for Fmoc solid-phase peptide synthesis. Short chains assemble in a single linear sequence with no need for fragment ligation, and the base-labile Fmoc protecting strategy with mild acidic cleavage keeps the acidic side chains intact through the build. For a peptide this size, the chemistry is routine rather than demanding.
The points that need care are the acidic positions. The glutamate and aspartate side-chain carboxyls are protected during chain assembly and unmasked cleanly at cleavage, and the aspartate position in particular is watched for the aspartimide side reaction that short acidic sequences can show under prolonged base exposure. Because the chain is so short, coupling efficiency is rarely the limiting factor; the work is mostly in clean deprotection and in a purification step that resolves the target from closely related sequences. The same general approach is used across the catalog for compact peptides such as the SS-31 tetrapeptide.
Characterization
Identity and purity for Epitalon are established with the same two complementary methods used across the reference catalog. Reversed-phase HPLC reports the purity profile, the percentage of total peak area attributable to the target peptide, and separates the main product from related deletion or truncation sequences. Mass spectrometry confirms identity by matching the measured mass to the expected mass for the Ala-Glu-Asp-Gly sequence.
Reading these together is what matters. An HPLC purity figure describes how much of the sample is the intended peptide relative to other UV-absorbing species, while the mass result confirms that the main peak is the right molecule rather than a same-length impurity. A small acidic peptide like this elutes early on a reversed-phase column and carries no aromatic chromophore of its own, so detection leans on low-wavelength backbone absorbance, a practical detail worth knowing when interpreting the trace. Both pieces of information describe the chemistry of the sequence, and a research chemist should expect to interpret them side by side.
Stability and Storage
As a lyophilized powder, Epitalon is comparatively stable when kept cold, dry, and out of light. Long-term storage of the dry solid is typically at freezer temperatures, with the container protected from moisture so the powder does not pick up water on opening. Allowing a sealed vial to reach room temperature before it is opened helps avoid condensation on the cold contents, which is good practice for any small hygroscopic peptide.
Once reconstituted, the working solution is less forgiving. Peptides in solution are subject to hydrolysis and adsorption to surfaces, so reconstituted material is generally held cold and used within a short window, with freeze-thaw cycles minimized. These are general handling principles for research peptides rather than claims about any one preparation, and the documentation for a given standard, available on request, should be the reference of record for its own conditions.
What Epitalon Is Studied For (Chemistry Only)
In a research-chemistry context, Epitalon is of interest as a clean model system for working with short acidic peptides. Its plain Ala-Glu-Asp-Gly sequence makes it a compact case study in synthesis and analysis: chemists can examine how acidic side chains affect solubility, how a sequence with no chromophore and no modifications behaves on a reversed-phase column, and how a short linear peptide is best stabilized in the dry state and in solution.
That framing is deliberately limited to the bench. These materials are reference standards for laboratory research only, and nothing here describes or implies any human or veterinary use or outcome. The value of Epitalon to a research chemist is as a chemistry subject, a small well-defined sequence whose behavior under synthesis, analysis, and storage is understood and worth knowing in detail. For broader context on how these standards are produced and verified, see the Research Overviews hub.
This overview is provided for laboratory and research use only. It is educational chemistry reference material and is not for human or veterinary consumption. Buyers are responsible for compliance with all applicable laws and regulations.
Epitalon, in brief
What is Epitalon and what is its sequence?
Epitalon is a short linear tetrapeptide with the sequence Ala-Glu-Asp-Gly, four residues joined in a single unbranched chain. Two of those residues, glutamate and aspartate, carry acidic side chains, which gives the peptide an overall acidic character. It is a small, well-defined sequence assembled by standard solid-phase methods.
What family does Epitalon belong to?
Epitalon is grouped with the short linear research peptides and is catalogued under the Other Compounds class. It is not a receptor analog or a copper complex; it is a simple acidic tetrapeptide studied as a compact, well-characterized sequence, which makes it a clean reference point alongside other short peptides in the catalog.
How is Epitalon synthesized and characterized?
Epitalon is assembled by Fmoc solid-phase peptide synthesis, which suits a short linear tetrapeptide. Identity and purity are confirmed using reversed-phase HPLC for the purity profile and mass spectrometry to match the measured mass to the expected sequence. These are standard analytical methods used across the reference catalog.
How should Epitalon be stored?
As a lyophilized powder, Epitalon is kept cold, dry, and out of light, with the dry solid typically held at freezer temperatures and protected from moisture. Once reconstituted it is held cold, used within a short window, and freeze-thaw cycles are minimized. These are general handling principles for research peptides.