Sermorelin in Canada: A Lab Guide to the GHRH 1-29 Fragment

Research groups ordering sermorelin in Canada are often running comparisons across the growth hormone-releasing hormone (GHRH) analog family, and sermorelin is the natural baseline for that work. It is the shortest fully active fragment of the native hormone, with no engineered changes to its residues. That makes it the cleanest reference point in a study, and also the most chemically exposed member of the group. This guide sets out what the molecule is, where its weak points lie, how it differs on paper from its modified relatives, and how to handle it across a multi-vial order.

Sermorelin in Canada: what arrives in the vial

Sermorelin is GHRH(1-29)-NH2: the first twenty-nine residues of human GHRH, finished with a C-terminal amide. The figures a certificate should match are:

It is supplied as a lyophilised powder, and like most synthetic peptides it is a salt, so the label weight includes counter-ions and some residual water as well as peptide.

How the 29-residue fragment was chosen

Native human GHRH is forty-four residues long. Structure-activity work in the literature showed that the N-terminal twenty-nine residues carry essentially all of the activity at the GHRH receptor, while the remaining fifteen add little. Cutting the chain at residue 29 gives a much shorter, cheaper peptide to make without giving up receptor activation. The same fragment later became the scaffold for engineered analogs, which is why so many GHRH-related compounds share its first twenty-nine positions.

What sets sermorelin apart is that nothing else was changed. It carries no substitutions, no fatty acid chain, no N-terminal cap and no albumin-binding group. For a comparison study, that is exactly the point: it shows what the native fragment does before any stabilising change is added.

The weak points written into the sequence

Because it is unmodified, sermorelin keeps every vulnerability of the native fragment. Knowing where they sit helps when interpreting both certificates and assay data.

• Tyr-Ala at the N-terminus. Dipeptidyl peptidase-4 (DPP-4) removes N-terminal dipeptides when the second residue is alanine or proline. Cleavage after Ala2 leaves GHRH(3-29), which has lost key receptor-binding residues. In any cell system or medium with DPP-4 activity, the peptide is being degraded during the experiment.
• Methionine at position 27. Oxidation to the sulfoxide adds 16 Da, giving a species near 3373.9. It can form during storage as well as synthesis.
• Asparagine at position 8. Followed by serine, this asparagine is a plausible deamidation site. Deamidation adds just under 1 Da and can produce closely eluting variants.
• The C-terminal amide. Activity at the receptor depends on it. The free-acid form differs by under 1 Da and is easily overlooked unless a certificate quotes the amidated mass.

The engineered analogs exist largely to fix these points. Our article on peptide half-life and analog modifications covers the general strategies.

Sermorelin versus Mod GRF 1-29 on a certificate

The most common identity mix-up in this family is between sermorelin and the tetrasubstituted fragment sold as Mod GRF 1-29 or CJC-1295 without DAC. Both are twenty-nine residues and both are amidated. Four substitutions separate them, and together they shift the mass by about 10 Da:

So sermorelin sits near 3357.9 and Mod GRF 1-29 near 3367.9, and Mod GRF 1-29 contains no sulfur. One subtle catch: the D-Ala substitution changes nothing in the mass, so a certificate cannot confirm it by MS alone. The CJC-1295 DAC and no-DAC guide explains those substitutions in detail, and tesamorelin is covered separately.

Using sermorelin as a benchmark in receptor assays

Sermorelin acts at GHRHR, which belongs to class B of the GPCR superfamily alongside the secretin and glucagon receptors. It signals mainly through Gs, which raises intracellular cAMP, so cAMP accumulation or a cAMP reporter is the usual in-vitro readout.

When sermorelin serves as the reference agonist in a comparison of analogs, a few habits keep the data comparable:

1. Run it on every plate, not just the first, so potency shifts between runs can be spotted.
2. Consider a DPP-4 inhibitor or a medium with low peptidase activity if the design is about receptor activity rather than stability.
3. Keep incubation times fixed, since degradation makes apparent potency time-dependent.
4. Do not pool results obtained with sermorelin and with a stabilised analog; they answer different questions.

For how this receptor pathway compares with the ghrelin-receptor route, see GHRH analogs versus growth hormone secretagogues.

Handling a 29-residue peptide across a large order

Longer peptides with helical tendencies can aggregate in solution, and sermorelin’s methionine adds oxidation risk. For a lab drawing on one lot for months:

• Keep unopened vials cold, dry and dark, and let each warm to room temperature before opening.
• Make one concentrated analytical stock, split it into single-use portions, and avoid refreezing.
• Use fresh, peroxide-free solvents to protect Met27.
• Calculate concentrations from net peptide content, not label weight; the net peptide content guide explains why.
• If the lot is re-tested later, check for growth of the +16 Da and deamidation signals.

We stock sermorelin in 5mg and 10mg vials within our growth hormone pathway range, shipped from within Canada. Volume pricing is mix-and-match, so sermorelin, CJC-1295 without DAC and tesamorelin vials for a comparison study all count toward one volume break. Products are third-party tested for purity by HPLC, certificates are published for some products on our certificates of analysis page, and cap and crimp colour ties each vial to its certificate.

Sermorelin is supplied by Bulk Peptides for in-vitro laboratory research only. It is not for use in humans or animals, and nothing in this article describes such use.

Buying several GHRH analogs for one programme? Compare prices per mg by tier in sermorelin vs tesamorelin vs CJC-1295.