Tesamorelin Peptide in Canada: A Stabilised Full-Length GHRH Analog

Most growth hormone-releasing hormone analogs on the research market are shortened versions of the natural molecule. Tesamorelin takes the opposite approach: it keeps the full 44-residue chain and adds one small chemical group at the very start. For labs looking at the tesamorelin peptide in Canada, that design choice shapes its mass, its stability profile and the impurities worth watching for. This article explains the structure, compares it with the other GHRH analogs you are likely to see on the same price list, and sets out what to check on a volume order.

Starting point: native GHRH and its weak spot

Human growth hormone-releasing hormone (GHRH) is a 44-amino-acid peptide with an amidated C-terminus. It acts at the GHRH receptor, a class B G protein-coupled receptor on pituitary somatotroph cells that signals mainly through Gs and cyclic AMP. Structure-activity work established long ago that the first 29 residues carry the receptor-binding activity, which is why so many analogs are built on GHRH(1-29).

The native hormone has a well-known vulnerability near its N-terminus. The enzyme dipeptidyl peptidase-4 (DPP-4) removes the first two residues, Tyr1 and Ala2, cutting the chain between positions 2 and 3. The truncated product binds the receptor poorly, so in biological matrices native GHRH loses activity quickly. Every GHRH analog is, in part, an answer to that problem.

How tesamorelin is built

Tesamorelin keeps the entire native sequence, residues 1 to 44 with the C-terminal amide, and attaches a trans-3-hexenoyl group to the amino group of Tyr1. That six-carbon acyl cap changes the N-terminus enough that DPP-4 no longer processes it efficiently, while leaving the rest of the chain untouched.

Key reference data for identity checks:

• Length: 44 residues plus the N-terminal hexenoyl group
• Molecular formula: C221H366N72O67S
• Molecular weight: about 5136 g/mol as the free base
• Usual salt form: acetate, which adds weight to the vial that is not peptide

Because the sequence beyond the cap is native, tesamorelin carries all of the natural residues, including some that the shorter synthetic analogs deliberately removed. That has consequences for stability and impurity profiles, covered below.

The cap itself is also useful analytically. Adding the hexenoyl group increases the mass by about 96 Da compared with unmodified GHRH(1-44)-NH2, so a species sitting roughly 96 Da below the main peak in a mass spectrum points to uncapped chain, either from incomplete acylation or from a mislabelled vial. The extra hydrocarbon also makes the molecule a little more hydrophobic, which typically shows up as slightly later elution on reversed-phase HPLC than the uncapped peptide under the same gradient.

Comparing the GHRH analog family

Labs working in this area usually see four related products. The differences are structural and easy to confirm by mass:

At roughly 5136 g/mol, tesamorelin is far heavier than the 29-residue analogs, which fall between roughly 3350 and 3650 g/mol depending on modification. A mass spectrum settles which compound is in a vial at a glance.

What a stabilised N-terminus does not fix

The hexenoyl cap protects against one enzyme. It does nothing for the chemical weak points elsewhere in the native sequence, and those are the ones a QC lab sees in stored material:

• Methionine 27 can oxidise to the sulfoxide, producing a +16 Da species. Mod GRF 1-29 replaces this residue with leucine; tesamorelin keeps it.
• Asparagine 8 is prone to deamidation, giving +1 Da products that often elute near the main peak. Again, the shorter modified analog swaps it out; tesamorelin does not.
• Length-related impurities. A 44-residue synthesis leaves more room for deletion and truncation sequences than a 29-residue one. They tend to cluster close to the main peak on reversed-phase HPLC, so a chromatogram tells you far more than a single purity figure.

None of these are unusual for a long peptide. They simply mean that storage conditions, time in stock and the resolution of the purity method all deserve attention.

Receiving and storing tesamorelin peptide in Canada

For a multi-vial delivery, a consistent routine keeps the paperwork and the material aligned:

1. Check that the label and certificate describe tesamorelin, not a 29-residue analog, and that the stated mass is near 5136 g/mol.
2. Match each vial’s cap and crimp colour to the certificate where one is published, and record the pairing in your log.
3. Count vials against the packing slip and note the appearance of the freeze-dried solid.
4. Store sealed vials cold, dry and dark, around −20 °C for long-term holding, and let them reach room temperature before opening.
5. For analytical solutions, prepare only what the run needs and avoid repeated freeze-thaw cycles, which accelerate both oxidation and deamidation.

If you trend purity across a long-held lot, a slow rise in the +16 Da and +1 Da species is the pattern to look for. It usually points to storage conditions rather than the original synthesis.

Specifying a volume order

A written specification line prevents most identity mix-ups in this family: compound name, the full description (hexenoyl-GHRH(1-44)-NH2), molecular formula, expected mass, salt form and the minimum HPLC purity you will accept. Asking for one lot across the whole order keeps a long project under a single certificate.

Bulk Peptides stocks tesamorelin alongside the other analogs in our growth hormone secretagogue range. Our products are third-party tested for purity by HPLC, certificates are published for some products, and vials are matched to their certificate by cap and crimp colour. Pricing is mix-and-match, so every vial in the cart counts toward the volume break, and orders ship from within Canada.

Tesamorelin and the other analogs discussed here are sold by Bulk Peptides for in-vitro laboratory research only. They are not for human or animal use, and nothing in this article is guidance on any such use.