Short peptide bioregulators are two to four amino acids long. That makes their molecular weight something you can calculate by hand and compare against the certificate — which is not possible for any other compound class in a peptide catalogue.
It takes a minute and needs nothing but a residue mass table. This post shows the arithmetic, applies it to all five bioregulators in this catalogue, and then separates the chemistry — which checks out — from the evidence base, which is a different and weaker story.
The arithmetic
A peptide bond forms by removing a water molecule between two amino acids. So:
Molecular weight = sum of residue masses + 18.02
The 18.02 is one water molecule, added once regardless of chain length, because the chain has one free amine and one free carboxyl at its ends.
Residue masses for the amino acids these compounds use:
| Residue | One-letter | Average residue mass |
|---|---|---|
| Lysine | K | 128.17 |
| Glutamic acid | E | 129.12 |
| Aspartic acid | D | 115.09 |
| Proline | P | 97.12 |
| Glycine | G | 57.05 |
| Arginine | R | 156.19 |
Peptide molecular weight from sequence covers the general method, including where monoisotopic and average masses diverge and why that matters for longer chains.
All five, checked
| Compound | Sequence | Calculation | Calculated | Certificate | Lot |
|---|---|---|---|---|---|
| Vilon | KE | 128.17 + 129.12 + 18.02 | 275.31 | 275.3 | VILON20-0528 |
| Vesugen | KED | 128.17 + 129.12 + 115.09 + 18.02 | 390.40 | 390.4 | VESU20-0528 |
| Pinealon | EDR | 129.12 + 115.09 + 156.19 + 18.02 | 418.42 | 418.4 | PINE20-0803 |
| Testagen | KEDG | 128.17 + 129.12 + 115.09 + 57.05 + 18.02 | 447.45 | 447.4 | TESTA20-0528 |
| Prostamax | KEDP | 128.17 + 129.12 + 115.09 + 97.12 + 18.02 | 487.52 | 487.5 | PROS20-0318 |
Every one matches to one decimal place. The small residuals — 390.40 against 390.4, 487.52 against 487.5 — are rounding in the residue table, not disagreement.
Why this is worth doing. The identity line on a certificate is the line that says the vial contains what the label claims, and for most compounds you have to take it on trust because verifying it requires a mass spectrometer. Here you do not. Two to four residues is short enough that the arithmetic is the verification.
If a bioregulator certificate reported a mass that did not match its stated sequence, you would know immediately, with a calculator. That is a genuinely unusual position for a buyer to be in — how to verify a certificate of analysis covers the checks available for everything else.
What these two compounds are
Vesugen is Lys-Glu-Asp. Prostamax is Lys-Glu-Asp-Pro — Vesugen with a proline on the end.
That relationship is typical of the family. Vilon is the KE dipeptide; Testagen is KEDG; Prostamax is KEDP. Three of the five are the same KED core with a fourth residue appended or removed. They are variations on a short acidic-basic motif rather than five unrelated molecules.
What a peptide bioregulator is covers the concept and its origins, and Khavinson short peptides compared sets the whole family side by side.
Handling: short peptides are not simply easier
Being tiny changes the practical behaviour in ways that are not all favourable.
| Property | Consequence |
|---|---|
| Solubility | High. Charged residues dominate and there is no hydrophobic core |
| Structure | None to speak of. Nothing to denature, nothing to aggregate |
| Adsorption | Proportionally significant — small, charged molecules bind surfaces and the loss is a larger fraction of a small quantity. Why peptides stick to plastic |
| Detection | Weak at 214 nm. A tripeptide has two peptide bonds; absorbance is low and peaks are small even when the compound is abundant |
| Stability | Good when lyophilized; the exposed termini are the vulnerable points in solution |
The detection point has a direct consequence for reading certificates: why tripeptides behave differently in solution and reading a certificate for a tripeptide both cover why a small peak does not mean a small quantity, and why area percent is a weaker number for this class than for longer chains.
The evidence, stated plainly
The chemistry is verifiable. The biology is not in the same condition, and it would be dishonest to present them as equally solid.
The short-peptide bioregulator literature originates substantially from one research group — Khavinson and collaborators at the St Petersburg Institute of Bioregulation and Gerontology — across several decades. Much of it is published in Russian-language journals or in supplements with limited circulation. Independent replication by unaffiliated laboratories is sparse.
That is not an accusation of error. It is a description of the evidence base's structure, and it is the single most important thing to know before reading any individual result. A finding reported repeatedly by one group is a different kind of evidence from one reproduced across independent laboratories.
Khavinson bioregulators: what the evidence actually shows goes through this in detail. The general problem of reading across from a narrow evidence base is covered in why trial data does not transfer.
A correct molecular weight tells you the vial contains the stated molecule. It tells you nothing about whether that molecule does anything. Those are separate questions and a certificate only answers the first.
Regulatory position
None of these compounds is an approved drug in the United States, European Union or other major markets. They are supplied for laboratory research only — what "research use only" means.
Frequently asked questions
Why can I calculate these masses but not a longer peptide's?
You can calculate any peptide's mass the same way; the method does not change. For a 43-residue protein it is forty-three lookups and a sum, and rounding errors accumulate. For three residues it is quick and the result is unambiguous.
Why add 18.02?
One water molecule, released when amino acids join. It is added once per chain, not once per bond.
What is the difference between Vesugen and Prostamax?
One proline. Vesugen is KED; Prostamax is KEDP.
Should I use monoisotopic or average mass?
Average, for this check. Certificates for short peptides generally report average mass, and the figures above use average residue masses. The two diverge more as chains lengthen.
Does matching arithmetic prove the material is pure?
No. It confirms the identity line is internally consistent with the stated sequence. Purity, content and endotoxin are separate measurements answering separate questions.
Why are the chromatogram peaks so small?
Because absorbance at 214 nm comes mainly from peptide bonds, and a tripeptide has two. Small peaks are expected for this class and do not indicate a small quantity.
References
- Khavinson VK. Peptides and Ageing. Neuroendocrinology Letters 2002;23 Suppl 3:11-144. pubmed.ncbi.nlm.nih.gov/12374906
- Anisimov VN, Khavinson VK. Peptide bioregulation of aging: results and prospects. Biogerontology 2010;11(2):139-49. doi.org/10.1007/s10522-009-9249-8
- International Union of Pure and Applied Chemistry. Atomic weights of the elements. iupac.org/what-we-do/periodic-table-of-elements
Every product mentioned is sold for laboratory research use only and is not for human or animal use. Nothing on this page describes or recommends use of the material sold here in humans or animals.
