Testagen is a synthetic four-residue peptide with the sequence Lys-Glu-Asp-Gly (KEDG, CAS 1026993-38-3, 447.44 g/mol), and Livagen is its one-residue sibling Lys-Glu-Asp-Ala (KEDA); both belong to the Khavinson family of short peptides and are supplied as lyophilized powders for in vitro research into nucleic-acid interaction and gene-expression readouts. This guide explains what the compounds are at the level of sequence and chemistry, how they relate to the other short peptides in the catalog, and how a laboratory confirms identity before use.
What is the Testagen peptide?
Testagen is a tetrapeptide: four amino acids joined by three peptide bonds. Written N-terminus to C-terminus the sequence is L-lysine, L-glutamic acid, L-aspartic acid, glycine, abbreviated KEDG or H-Lys-Glu-Asp-Gly-OH. Two of the four residues (Glu and Asp) carry acidic side chains and one (Lys) carries a basic side chain, so at neutral pH the molecule is a small, highly polar zwitterion. That polarity is why it is water-soluble and why it is handled as a lyophilized powder rather than a solution.
The name "Testagen" is a catalog name from the Khavinson short-peptide series, not a chemical descriptor. In a research context the compound is defined by its sequence and identifiers, and that is how it should be referred to in methods sections and on a Certificate of Analysis.
What are Khavinson short peptides?
Khavinson short peptides are a family of synthetic di-, tri- and tetrapeptides built from a small set of charged and polar residues, most of them glutamate, aspartate, lysine, arginine, glycine and alanine. They are studied in vitro as short-peptide bioregulator research compounds: the laboratory question is how a very short, highly charged peptide interacts with nucleic acids and whether that interaction shows up in gene-expression assays in cultured cells. The catalog carries five members of the family, and they are easiest to keep straight in a table.
| Catalog name | Sequence | Length | CAS number | Formula | MW (g/mol) |
|---|---|---|---|---|---|
| Testagen | Lys-Glu-Asp-Gly (KEDG) | 4 | 1026993-38-3 | C17H29N5O9 | 447.44 |
| Livagen | Lys-Glu-Asp-Ala (KEDA) | 4 | 433257-50-2 | C18H31N5O9 | 461.47 |
| Epithalon | Ala-Glu-Asp-Gly (AEDG) | 4 | 307297-39-8 | C14H22N4O9 | 390.35 |
| Cartalax | Ala-Glu-Asp (AED) | 3 | 85806-95-7 | C12H19N3O8 | 333.29 |
| Pinealon | Glu-Asp-Arg (EDR) | 3 | 175175-23-2 | C15H26N6O8 | 418.41 |
Notice the shared Glu-Asp core. Testagen and Epithalon are identical in their last three residues and differ only at the N-terminus (lysine versus alanine); Testagen and Livagen are identical in their first three residues and differ only at the C-terminus (glycine versus alanine). The tripeptide Cartalax (Ala-Glu-Asp) is Epithalon without its C-terminal glycine. These single-residue differences are the whole story when confirming which compound is in a vial.
How do Testagen and Livagen differ?
By one carbon. Replacing the C-terminal glycine of Testagen with alanine adds a single methyl group, which raises the molecular formula from C17H29N5O9 to C18H31N5O9 and the molecular weight by 14.03 g/mol, from 447.44 to 461.47. The charge pattern, solubility and handling are otherwise the same. Because the two are so close, the only reliable way to tell them apart is mass spectrometry, as described below; appearance, solubility and even HPLC retention time are not enough on their own. Livagen has its own profile in Livagen peptide: sequence and research framing.
How are these short peptides studied in vitro?
The work is mechanistic and cell-based. Typical designs use cultured cells exposed to the peptide at defined molar concentrations, with readouts such as messenger-RNA levels by quantitative PCR, reporter-gene activity, or chromatin-accessibility measurements, always against vehicle controls and, ideally, a scrambled-sequence peptide control of the same length and charge. The methods are described in gene-expression assays in vitro. Because Testagen, Livagen and Epithalon share most of their sequence, running them side by side at matched molarity is a natural way to ask whether a single residue change alters a readout.
How do you confirm you have Testagen and not Livagen or Epithalon?
Three checks on the Certificate of Analysis settle it:
- Mass spectrometry. The observed [M+H]+ for Testagen should be about 448.2; Livagen gives about 462.2 and Epithalon about 391.1. A 14-unit difference is unambiguous on any modern instrument.
- HPLC purity. A single dominant peak, reported as a percentage of total area; the catalog specification is approximately 99%.
- Identifiers. The CAS number and sequence printed on the COA should match the product page. The line-by-line COA guide shows where each item appears.
Stock concentration math for a 20 mg vial
Testagen is listed as a 20 mg vial. Reconstituting the full vial in 1 mL of reconstitution solution gives 20 mg/mL, which at 447.44 g/mol is a 44.7 mM stock; 2 mL gives 10 mg/mL (22.4 mM) and 4 mL gives 5 mg/mL (11.2 mM). Working solutions in the micromolar range are then made by serial dilution in assay medium. The arithmetic is the same as in the reconstitution math guide; use molarity, not mass, when comparing Testagen with Livagen, because the two have different molecular weights.
Related research guides
- Livagen peptide: sequence and research framing
- Short-peptide bioregulator research compounds: an overview
- Pinealon: a tripeptide bioregulator
- Epithalon: a tetrapeptide bioregulator
- Cartalax: the AED tripeptide, sequence and identity
- Mass spectrometry for peptide identity confirmation
Research-use note
All materials discussed are supplied for in vitro laboratory research use only, and are not for human or animal use.
