GH/IGF-1 axis research
Work on GHRH receptor signalling and somatotroph response, where the C-terminal amide and the full 44-residue length are both part of the molecule under study.
Peptide · Growth hormone axis
Tesamorelin (GHRH 1-44 analogue)
A 5,135 Da GHRH analogue delivered as the acetate. On this molecule the number that decides your weighing is not purity — it is peptide content, and it is lower than most buyers expect.
Also known as Tesamorelin · TH9507 · GHRH(1-44) analogue · Egrifta
Overview
What Tesamorelin is
Tesamorelin is a 44-residue analogue of growth-hormone-releasing hormone, amidated at the C-terminus and supplied as the acetate salt. At 5,135.78 g/mol it is one of the larger peptides in the catalogue, and size changes what goes wrong: the longer the chain, the more truncated sequences survive synthesis, and the harder the purification step has to work.
The practical trap is arithmetic. A certificate reading 99.24% purity looks like almost pure peptide. Peptide content is 82.1%, acetate is 8.3% and water is 7.5% — so a 10 mg weighing contains about 8.2 mg of peptide. Formulators who weigh against the label rather than the peptide content run roughly 18% light, and the error is invisible on the balance.
Both figures are on the certificate for this reason, stated separately rather than folded into a single number. The current lot assays 99.24% with a largest single impurity of 0.4%.
- ≥ 98.0% by HPLC; current lot 99.24%, largest single impurity 0.4%
- Peptide content 82.1% and acetate 8.3% reported as separate lines
- Water content 7.5%, inside the ≤ 8.0% limit but worth watching at re-test
- C-terminal amide confirmed by ESI-MS
Identity
The record.
The identifiers your specification sheet, customs paperwork and product label all have to agree on. Where a number depends on the salt form, both are given.
- Chemical name
- GHRH(1-44) analogue, C-terminal amide, acetate salt
- Common name
- Tesamorelin; TH9507
- CAS number
- 218949-48-5
- Molecular formula
- C₂₂₁H₃₆₆N₇₂O₆₇S
- Molecular weight
- 5135.78 g/mol
- Residue count
- 44 (C-terminal amide)
- Counter-ion
- Acetate, 8.3% on the current lot
- Appearance
- White powder
- Peptide content
- 82.1% (nitrogen determination)
- Water content
- ≤ 8.0% (Karl Fischer)
- Storage
- −20 ± 5 °C, sealed, protected from light
- Retest period
- 24 months from manufacture
HS codes are indicative only. Final classification is confirmed per shipment with your customs broker.
Manufacture
How it is made.
Forty-four residues is where synthesis yield and impurity profile start to matter commercially, not just analytically.
- 01
Solid-phase assembly
The 44-residue chain is built stepwise. Each coupling that does not go to completion leaves a truncated sequence that is one residue short of the target and chemically very similar to it — the hardest class of impurity to remove.
- 02
C-terminal amidation
The amide is introduced during cleavage. It is part of the molecule, and a certificate that reports mass without confirming the amide is reporting the wrong mass.
- 03
Preparative HPLC
Gradient purification against the full-length product. The largest-single-impurity figure is the honest measure of how much truncation survived this step.
- 04
Acetate exchange and drying
The peptide is converted to the acetate and lyophilised. Acetate and water together account for roughly 16% of the powder, which is why peptide content is reported separately.
Applications
Where it is used.
Supplied to laboratories studying the growth-hormone axis. Research use only — we do not supply clinical, dosing or administration information.
Analytical method development
Used as a reference standard for long-chain peptide methods, where an 82.1% peptide content is the number that has to go into the calculation, not the purity.
Formulation and stability work
A large, amide-terminated peptide with a defined acetate load, useful for studying aggregation and deamidation behaviour in solution.
Specification
Release criteria.
The written limits we release against, with the method used to test each one. Batch results for the lot you receive are stated on its certificate of analysis.
| Parameter | Limit | Method |
|---|---|---|
| Appearance | White powder | Visual |
| Identity | Conforms to reference | ESI-MS |
| Purity | ≥ 98.0% | HPLC |
| Acetate content | ≤ 12.0% | HPLC |
| Water content | ≤ 8.0% | Karl Fischer |
| Peptide content (N) | ≥ 80.0% | Nitrogen determination |
| Mass balance | 95.0 – 105.0% | Calculation |
| Dichloromethane residue | ≤ 0.060% | GC |
| DMF residue | ≤ 0.088% | GC |
| Bacterial endotoxin | < 10 EU/mg | LAL |
| Total aerobic count | ≤ 100 cfu/g | Plate count |
| Mould & yeast | ≤ 100 cfu/g | Plate count |
| Shelf life | 24 months from manufacture | Stability programme |
Tighter limits — for example a lower heavy-metal ceiling or a residual-solvent panel — can be quoted against your own specification wording.
Certificate
Reading the certificate.
Long peptides carry more of their quality in the secondary numbers than short ones do.
Peptide content, not purity, decides your weighing
At 82.1% peptide content and 8.3% acetate, a 10 mg weighing is about 8.2 mg of peptide. Every concentration calculated from the label weight is roughly 18% low, and nothing in the experiment will show it.
Check that the amide is confirmed
The C-terminal amide changes the mass by 1 Da and the charge profile noticeably. A certificate that reports a conforming mass without stating the expected value is not confirming identity — ask for the number.
Water at 7.5% leaves little headroom
The limit is ≤ 8.0%. Material released close to a water limit has less margin at re-test, particularly if the vial has been opened. If your protocol is moisture-sensitive, ask for the current lot's figure before you commit to a bulk quantity.
Documentation & packaging
What ships with it.
The paperwork travels with the goods. If your QA team needs an extra declaration, ask before the order is released — some are issued per production lot and cannot be retrofitted.
Certificate of analysis
Purity, acetate, water, peptide content, mass balance and microbiological results for the lot supplied.
Identity data
ESI-MS result for the full-length, C-terminally amidated peptide.
SDS & specification
Safety data sheet and the enterprise standard the batch is released against.
Batch documentation
Lot number, manufacture date and retest date; a certificate on our own template is issued with the shipment.
| Pack size | Presentation | Typical use |
|---|---|---|
| 1–10 g | Amber vial, 10 mL | Evaluation |
| 25–50 g | Amber vial, 50 mL | Pilot scale |
| 100 g | Amber vial, 100 mL | Small commercial |
| 1 kg+ | Foil bag, quoted per order | Bulk |
Questions
Before you order.
The questions buyers actually ask about Tesamorelin. Anything not covered here, ask directly — you will get an answer from someone technical, not a template.
Why is peptide content only 82.1%?
Because the powder is not all peptide. Acetate accounts for 8.3%, water for 7.5%, and the remainder is counter-ion and residual salts. 82.1% is the peptide fraction, measured by nitrogen determination — it is a normal figure for an acetate salt of a large peptide.
Should I weigh against purity or peptide content?
Peptide content, always. Purity describes how clean the peptide is relative to its own impurities; peptide content describes how much of the powder is peptide at all. Concentrations calculated from the label weight will be about 18% low on this material.
Is this the same as CJC-1295 with DAC?
No. Tesamorelin is a 44-residue GHRH analogue with a C-terminal amide and no drug-affinity complex. CJC-1295 with DAC is a different molecule with a different mass, a different half-life strategy and a different counter-ion (TFA). The two are not interchangeable and their documentation is not interchangeable either.
Is the C-terminus amidated?
Yes, and it is part of the specification. The amide is introduced at cleavage and confirmed by mass spectrometry; the free-acid form would be a different molecule with a different mass.
How should it be stored?
−20 ± 5 °C, sealed and protected from light. Equilibrate the vial to room temperature before opening so condensation does not land on the cake.
Can you supply a lot with lower water content?
Ask. Drying to a tighter water specification is possible on a made-to-order batch, and for a moisture-sensitive protocol it is worth specifying up front rather than discovering at re-test.
Related
Often quoted together.
Quotation
Ask for Tesamorelin, by the gram.
Send the quantity, the grade you need and the destination. You will get a written quotation with lead time, packaging options and the documentation set for this material.