Tesamorelin: structure and analysis

What it is

Tesamorelin is a synthetic analog of the full 44-amino-acid growth hormone-releasing hormone, modified at the N-terminus with a trans-3-hexenoyl group. It is built on the complete sequence rather than the 1-29 fragment that sermorelin and CJC-1295 without DAC use.

At 44 residues it is the longest GHRH-derived compound in this catalogue and among the longest synthetic peptides in it.

The trans-3-hexenoyl group is an acyl modification — a small unsaturated chain attached to the N-terminal amine — and its function is to slow enzymatic degradation of the native sequence.

How it is produced

Assembled by solid-phase peptide synthesis: the chain is built one residue at a time on an insoluble resin support, then cleaved from the resin, deprotected and purified — most commonly by reversed-phase high-performance liquid chromatography. The purified material is lyophilized to a dry solid.

The impurity profile that appears on a certificate is a record of where that process was imperfect: deletion sequences from an incomplete coupling, truncated chains, and species retaining a protecting group.

Confirming identity

Mass spectrometry confirms both the 44-residue chain and the N-terminal acyl modification. The hexenoyl group adds a distinct mass increment, so unmodified sequence is a clearly detectable impurity rather than an ambiguous one.

The mass also separates this compound unambiguously from the two 1-29-based GHRH compounds in the catalogue, which are fifteen residues shorter.

Analytical considerations

Forty-four coupling steps make this the most demanding synthesis in the catalogue outside the recombinant protein. Deletion sequences are the dominant impurity class and are numerous, so chromatographic resolution is the limiting factor on how informative a purity figure can be.

Incomplete acylation is the modification-specific impurity. Because the acyl group increases hydrophobicity, modified and unmodified species separate reasonably well on reversed phase, so mass and retention tend to agree.

As with the other GHRH-derived compounds, the identity result is what establishes which member of the family is present. Sermorelin, CJC-1295 without DAC and this compound are three different molecules.

What its certificate reports

A certificate for a lot of this material names the lot, names the issuing laboratory, and states for each parameter both the method used and the specification the result was measured against. Identity and purity are the two core results; net peptide content states how much of the fill weight is actually peptide.

A certificate belongs to a lot, not to a product line. When a new lot is released it is tested again, and the certificate published against it is that lot's certificate — a previous lot's result is never carried forward.

Research use only

This page describes structure and analysis. It makes no claim about what this compound does, and none should be inferred from it. Material is supplied for laboratory research use only: it is not a drug, food, dietary supplement, cosmetic or medical device, it is not for human or veterinary consumption, and no dosing, administration or reconstitution guidance is provided for any such use.