Epitalon (Ala-Glu-Asp-Gly): preparation and storage
Intended for research use only. Not a medicinal product.
Contents (8 sections)
Identity and material form
Epitalon, also spelled Epithalon, is the defined synthetic tetrapeptide Ala-Glu-Asp-Gly, abbreviated AEDG. It differs from Epithalamin, a multicomponent pineal extract. AEDG can be described by one sequence and molecular weight; an extract cannot. Keep the names distinct on tubes and in result tables.
MedChemExpress uses the spelling Epithalon and lists 390.35 g/mol for the described molecule. Before conversion to molarity, check salt form, terminal groups and peptide content. Water and counterions in a lyophilisate are not part of the AEDG sequence, but affect its peptide mass fraction.
What the research context means
Khavinson, Bondarev and Butyugov added Epithalon to human fetal fibroblast cultures and examined telomerase catalytic-subunit expression, enzymatic activity and telomere length [1]. This was a specific cell model. Its result is neither a reagent stability interval nor an established outcome for every cell type or organism.
Repeating such an experiment requires attention to passage number, culture condition and exposure time. Starting cell number and signal normalisation can affect comparisons. Prepare stock separately from final medium and match its solvent to an AEDG-free control. Prolonged cell exposure requires checking peptide preservation in the medium itself.
Solvent and final matrix
The two acidic side chains make pH relevant to AEDG dissolution. The sequence alone nevertheless does not establish the solubility of a particular lyophilisate. Select the batch-recommended solvent and first test a small volume. Adding strong base “until clear” creates a new chemical condition that may be absent from the original method.
Check the solution after transfer into salt- and protein-containing medium, rather than only in water. A pH shift matters especially in small, weakly buffered volumes. Do not use a preservative to extend storage without validation: it may affect cells, and absence of microbial growth does not establish AEDG preservation.
Laboratory calculation example
For pure AEDG at 390.35 g/mol, 0.39035 mg in a final 1.000 mL corresponds to 1.000 mmol/L. Obtaining 5.00 µmol/L in 2.00 mL requires 10.0 µL of stock, brought to a final 2.00 mL. This is an arithmetic example rather than a reproduction of the paper's concentration or a recommended exposure.
If the certificate gives only nominal total vial mass, record nominal mg/mL. Do not multiply that mass by HPLC purity to imply an exact content: peak area and quantitative mass fraction are different measurements.
Quality checks during handling
AEDG has no aromatic Trp or Tyr residues, so a protein A280 measurement is not a suitable standalone concentration assay. Small quantities require a method validated for this peptide and matrix. Culture-medium components can interfere with nonspecific UV measurements.
For prolonged work with one batch, retain a control aliquot and compare chromatographic profile and quantitative recovery after storage. A changed biological signal alone does not identify the cause: cell variability, matrix or reagent may be responsible.
For a telomerase experiment, reagent controls and analytical-reaction controls are separate. In an amplification-based method, residual matrix can affect measurement independently of cell condition. Follow the requirements of that method rather than replacing them with an AEDG concentration measurement.
If only quantitative recovery falls after storage, check transfer and actual volume. New peaks require investigation of chemical changes. If analytical reagent measurements match while cell signals differ, check the culture and biological-assay execution. This avoids attributing every difference to “peptide instability” without evidence.
Use the same aliquot preparation scheme across passages. Do not top up an old remainder with fresh solution: the mixture then has no single age or sample history. Do not return unused material exposed to medium into the original stock.
Dry material and solution need separate conditions
For long-term storage of a dry synthetic peptide, use a freezer, commonly −20 °C or below, where the specification supports it. Allow the sealed vial to reach room temperature before opening so moisture does not condense on cold powder. A refrigerator at +2–8 °C can be a working option for dry material needed within a week or a month only when the supplier supports that interval. Planning to use a vial soon does not establish its shelf life.
A solution needs its own record: solvent, concentration, pH, preparation date, temperature and permitted holding time. Do not transfer the dry-material expiry to the solution. Where freezing is supported, prepare aliquots for individual experiments; thawing the remainder again needs separate validation. Bacteriostatic water contains a preservative that can change a cell-assay result and is not a default solvent for every peptide.
Practical questions
Can the same mass of Epithalamin replace AEDG? No. Extract mass describes a mixture; AEDG mass describes one molecule. Does absence of Trp guarantee long stability? No. It is one structural distinction; storage life requires data for the actual conditions.
Can prepared Epitalon medium stay refrigerated for a month? This page establishes no such interval. Separate data are needed for the dilute peptide and the medium itself.
Monograph · Product page · Certificates of analysis
General reagent preparation · Bacteriostatic water compatibility · Storage and expiry
Sources
- Khavinson V. Kh., Bondarev I. E., Butyugov A. A.. Epithalon Peptide Induces Telomerase Activity and Telomere Elongation in Human Somatic Cells. 2003.
MedChemExpress: epitalon. Reference characteristics of that catalogue material; not a specification for a Longeva batch.
End of article
Epitalon
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