Testagen

Testagen is a synthetic tetrapeptide from the Khavinson bioregulator series, the family of short peptides developed at the St Petersburg Institute of Bioregulation and Gerontology. Its sequence is Lys-Glu-Asp-Gly, written KEDG, with the molecular formula C17H29N5O9 and a molecular weight of 447.4 g/mol. PubChem holds the structure as CID 123863700, deposited from a chemical library rather than under the commercial name, so a database search on the word Testagen returns nothing. Material is supplied as a lyophilized (freeze-dried) solid.

The distinction worth leading with is from Epitalon, which is Ala-Glu-Asp-Gly, C14H22N4O9, 390.35 g/mol. Testagen carries the same three C-terminal residues with lysine in place of alanine at position one: a single substitution, a mass difference of about 57 Da, and one basic side chain added to a molecule that is otherwise acidic. They are neighbours in a series, not variants of one compound. No CAS number resolves for Testagen in a public database, so that field is reported as unassigned.

The programme behind Testagen began in the 1970s with polypeptide fractions from animal organs, then narrowed to short synthetic sequences said to reproduce their activity. The sequence enters PubMed-indexed work in 2008, in avian studies examining Lys-Glu-Asp-Gly alongside Ala-Glu-Asp-Gly, continued in a 2013 report on tissue morphology (PubMed 23658898).

Three primary papers carry most of the weight. A 2011 study followed fluorescence-labelled short peptides, testagen among them, into the nucleus of HeLa cells (PubMed 22117547). A 2013 companion paper reported binding of the same set to labelled wheat histones (PubMed 23581987). A 2025 paper from a Romanian chemistry group examined adsorption of the tetrapeptide on copper (PubMed 40807317).

The record is thin and should be described that way. A PubMed search on the name returns two items, and the sequence adds fewer than ten more, most from the originating group and several in Russian-language journals with English abstracts only. There is no published human trial, no toxicology package and no independent replication.

The mechanism proposed for this class is transcriptional rather than receptor-mediated. Its authors argue that peptides of two to four residues cross cell and nuclear membranes, contact DNA and the N-terminal tails of histones, and shift expression of a small set of genes. Testagen appears in the experiments used to support that argument (PubMed 22117547; PubMed 23581987) and in a docking study covering twenty-six ultrashort peptides (PubMed 36979488).

The lysine residue is the practical distinction. Epitalon and Cartalax are acidic across their length, while Testagen adds one basic side chain, so its net charge at neutral pH and its chromatographic behaviour differ.

Two caveats belong with those results. The nuclear penetration work used fluorescein-labelled peptides, a chemical modification of the molecule under study. The binding measurements are quenching constants from cell-free systems, and the transport paper is a model, not an experiment.

Sealed lyophilized Testagen is held frozen at -20°C, shielded from light, in its original container. Lyophilized peptides draw water from air, so a container reaches ambient temperature before it is opened.

Repeated freeze-thaw cycles are avoided. Stability for a lot is documented on its Certificate of Analysis rather than stated as a general duration.

Reconstitution means returning a lyophilized compound to solution. No preparation procedure appears here: solvent and concentration belong to a study protocol. Testagen carries two free carboxyl side chains and one free amine and is handled as aqueous-soluble material.

A four-residue peptide has no secondary structure to report and gives small signals in assays scaled for proteins. Solubility and water content appear on the lot COA.

Identity and purity of research-grade Testagen are established by reverse-phase HPLC and mass spectrometry. Verified purity is documented per lot on the Certificate of Analysis. Sequence confirmation is the specification to read first: the difference from Epitalon is one residue and about 57 Da, invisible to inspection but easily resolved by mass spectrometry.

Two things move the observed mass: short acidic peptides are often supplied as salts, and counter-ion content shifts what a balance reports. Very polar tetrapeptides also retain poorly on standard reverse-phase columns.

Testagen sits in a group of short peptides and preparations from one programme.

• Epitalon.
  The tetrapeptide Ala-Glu-Asp-Gly, differing at position one and the most published compound here.
• Cartalax.
  Indexed as the tripeptide Ala-Glu-Asp, the acidic core without a C-terminal glycine.
• Pinealon.
  The tripeptide Glu-Asp-Arg, the other series member carrying a basic side chain.
• Cardiogen and Prostamax.
  Further defined sequences from the programme, on the same evidence footing.
• Vilon, Ovagen and Thymalin.
  The dipeptide Lys-Glu, a compound with no settled sequence, and the preparation that preceded the synthetics.

Fedoreyeva LI, Kireev II, Khavinson VKh, et al. (2011). Penetration of short fluorescence-labeled peptides into the nucleus in HeLa cells and in vitro specific interaction of the peptides with deoxyribooligonucleotides and DNA. Biochemistry (Mosc).
PubMed 22117547

Fedoreyeva LI, Smirnova TA, et al. (2013). Interaction of short peptides with FITC-labeled wheat histones and their complexes with deoxyribooligonucleotides. Biochemistry (Mosc).
PubMed 23581987

Pateyk AV, Baranchugova LM, et al. (2013). Effect of peptides Lys-Glu-Asp-Gly and Ala-Glu-Asp-Gly on the morphology of the thymus in hypophysectomized young and old birds. Bull Exp Biol Med.
PubMed 23658898

Khavinson VK, Linkova NS, et al. (2023). Feasibility of Transport of 26 Biologically Active Ultrashort Peptides via LAT and PEPT Family Transporters. Biomolecules.
PubMed 36979488

Dobriţescu A, Samide A, Cioateră N, et al. (2025). The Inhibitory Effect and Adsorption Properties of Testagen Peptide on Copper Surfaces in Saline Environments: An Experimental and Computational Study. Molecules.
PubMed 40807317

Testagen is stocked in one format: a sealed lyophilized vial from a single supplier brand, listed at a 20mg fill. The per-vial strength is a product specification. Each lot is batch tested with a published Certificate of Analysis documenting verified purity and identity, the identity reference that counts for a compound with no public CAS record.

• Browse all Testagen research products
• Verified Peptides Testagen, 20mg lyophilized vial

These products are sold for Research Use Only and are not intended for human consumption.