Tesamorelin Peptide | 20mg | 3ml

Tesamorelin is a synthetic 44-residue analogue of human growth-hormone-releasing hormone — GHRH (1-44) — carrying a trans-3-hexenoyl group on its N-terminal tyrosine. Supplied at 20mg per vial.

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The molecule, and why the N-terminus is capped

Tesamorelin retains the complete GHRH (1-44) sequence, C-terminally amidated, and adds one six-carbon unsaturated acyl group at the amino terminus. That cap is the entire design intent of the analogue.

Native GHRH is an awkward reagent in any enzyme-containing system, because dipeptidyl peptidase-4 (DPP-4) cleaves after the position-2 alanine and removes the Tyr-Ala dipeptide that the GHRH receptor's binding pocket requires. What remains is a different ligand, not a weaker one. The trans-3-hexenoyl group acylates the alpha-amino group of the N-terminal tyrosine — it caps that free amine rather than occupying or replacing residue 1, and the sequence itself is unchanged. The added steric bulk obstructs DPP-4 recognition, so the intact 44-mer persists markedly longer than unmodified GHRH when the two are incubated side by side under identical in-vitro conditions. The receptor-contact residues, the helical mid-section and the C-terminal amide are left untouched.

Two practical consequences follow for a receiving laboratory. First, this is a large peptide by catalog standards — around 5.1 kDa, with the hexenoyl cap contributing roughly 96 Da over native GHRH. On LC-MS you should expect a multiply charged envelope rather than a tidy single-charge ion. Second, the helical region makes the molecule conformationally sensitive to organic content and buffer composition, so retention time is not transferable between methods — compare peaks only against a chromatogram run on your own gradient.

GHRH analogue and secretagogue are not interchangeable terms

Compounds in this corner of a catalog get grouped together loosely. They should not be: two different receptor families are involved.

The GHRH receptor is a class B G-protein-coupled receptor coupling principally through Gs and cAMP. GHS-R1a is a class A receptor coupling principally through Gq and phospholipase C. They are distinct proteins with distinct ligand requirements, and the reason these compounds appear in the same experimental designs is that laboratory work examines whether two separate signaling routes converge on shared downstream readouts in cell models — a receptor-pharmacology question, studied in vitro. If your protocol involves both receptor families, /products/hulk-stack pairs CJC-1295 with DAC and Ipamorelin as a single listing.

Two formats, two different sets of risks

Research peptide reaches a laboratory either as a lyophilized powder to reconstitute or already in solution. Neither format is inherently better; each moves the risk somewhere else, and it is worth being explicit about where.

A solution removes the largest single source of between-operator inconsistency; a powder gives longer dated storage and shrugs off a slow courier. Confirm which format a vial is before building an incoming-goods workflow around it, and assess the condition of what actually arrives rather than assume it.

Composition questions to ask about any vial

A stated strength describes peptide content, not vial content. Ask the supplier what else is present: the solvent system if the material is in solution, whether a preservative such as benzyl alcohol is included, whether the pH is buffered and to what, and whether the counterion is acetate or trifluoroacetate. TFA in particular is worth pinning down — residual trifluoroacetate is a known source of interference in cell-based assays and is easy to overlook when a COA reports only purity.

For a lyophilized vial, ask for water content by Karl Fischer and for counterion content, then work out net peptide mass before comparing prices per milligram between a powder and a solution.

Reading a Certificate of Analysis properly

A COA is a document about one lot, or it is decoration. Ours are published at /coa.

What a usable certificate contains: a lot number that matches the vial label; the analytical date; the method, column and gradient for the purity determination; the full chromatogram rather than a cropped image; a mass-spectrometry trace with the observed mass reconciled against theoretical; and the name of the laboratory that performed the work.

What should stop a purchase: no lot number, or a lot number that appears on multiple products; purity quoted without a method; a chromatogram with no axis labels or an obviously trimmed baseline; identical documents recycled across different compounds with the title swapped; and mass spectrometry omitted entirely, which leaves the identity of the peak unestablished. Purity tells you how much of the material is one thing. Only mass confirmation tells you which thing.

For a 44-residue peptide, identity confirmation matters more than it does for a short chain. Deletion sequences and truncations produced during synthesis can co-elute closely with the target and are separable on mass long before they are separable on retention time.

Origin and testing

This material is synthesized in the UK and verified in US laboratories. Stating both halves is deliberate: synthesis location and testing location are separate facts, and a supplier that blurs them is telling you less than it appears to.

Storage and handling

Peptide belongs cold and dark in either format. Protect from light, minimize freeze-thaw cycling by working from aliquots rather than the parent vial, and keep the vial upright and sealed between uses. The GHRH (1-44) sequence carries one methionine (Met27) and two asparagine residues (Asn8 and Asn35), which makes oxidation and deamidation the degradation chemistries to watch; both are accelerated by warmth, extremes of pH and repeated headspace exposure, and both run faster in solution than in a dry cake. Visible haze, precipitate or discoloration is a reason to quarantine a vial and re-assay, not to proceed.

Research context

The published work on tesamorelin is a body of in-vitro and animal laboratory research under examination — receptor binding and selectivity at GHRHR, proteolytic stability against DPP-4, and signaling characterization in cell systems. It is an active area of examination rather than a settled account, and nothing on this page draws conclusions from it. Tesamorelin appears on the WADA Prohibited List under section S2.