Description
PrymaLab · Research Use Only
Ipamorelin Peptide 10mg
A 1998 claim · and how it was demonstrated
Ipamorelin peptide was introduced in 1998 under a specific claim: that it was the first selective growth hormone secretagogue. Selectivity claims are common and this one was unusual because it came with the measurements that would have falsified it. That is worth more than the claim itself.
Specification Table
| Property | Value |
|---|---|
| Compound | Ipamorelin |
| Class | Growth hormone secretagogue, pentapeptide |
| Residue count | 5 |
| Molecular weight, calculated | Approximately 711.9 g/mol for the free base |
| CAS | 170851-70-4 |
| Receptor | GHS-R1a |
| Non-coded residues present | Two. An alpha-aminoisobutyric acid residue and a naphthylalanine residue |
| D-configuration residues present | Two, which is the principal reason for its protease resistance |
| Carboxy terminus | Amidated |
| First characterisation | Raun and colleagues, European Journal of Endocrinology, 1998 |
| Appearance | White lyophilized powder |
| Purity | Per lot-specific certificate of analysis |
| Solubility | Water soluble |
| Storage, lyophilized | 2-8°C short term, -20°C for extended storage, protected from light and moisture |
What Did the 1998 Selectivity Finding Actually Measure?
A selectivity claim is only as good as the things it was tested against, and this one named them.
The pituitary does not release growth hormone in isolation. Compounds acting on it can also move adrenocorticotropic hormone, cortisol, prolactin and other outputs, and earlier secretagogues did.
The 1998 characterisation measured those other outputs rather than measuring growth hormone alone and reporting a clean result by omission.
That is the methodological point. A compound tested only for the effect it was designed to produce cannot generate evidence of selectivity, because nothing was measured that could have contradicted it.
Ipamorelin peptide was compared against reference secretagogues in the same experimental system, which is what makes the comparison interpretable rather than anecdotal.
The finding was that growth hormone release occurred at concentrations where the other measured pituitary outputs did not move appreciably.
What follows from that is narrower than the way the result is usually repeated. It establishes a separation across a measured concentration range in a defined preparation.
It does not establish that no separation collapses at higher concentrations, in a different species, or on outputs nobody measured. Selectivity is a range statement rather than a property, and the published range is the useful part.
Why Is Ipamorelin Peptide Harder to Make Than Five Residues Suggests?
A pentapeptide sounds trivial to make and ipamorelin peptide is not, because two of the five residues are not standard amino acids.
Alpha-aminoisobutyric acid carries two methyl groups on the alpha carbon rather than one methyl and one hydrogen. That extra bulk makes the residue sterically hindered and slows the coupling step that attaches the next residue to it.
A slow coupling is an incomplete coupling. Chains that failed to react carry forward and appear in the final product as deletion sequences missing that residue.
Naphthylalanine is a bulky aromatic residue with the same consequence for the coupling that follows it.
So the two positions in ipamorelin peptide that are chemically distinctive are also the two positions where synthesis fails most often, and a deletion at either produces a peptide with the correct four remaining residues and the wrong pharmacology.
On a 712 dalton molecule a single deletion is a large proportional mass change, roughly ten to fifteen percent depending which residue is missing, which is the one advantage of working with a short peptide.
That change is unmissable on any mass spectrometer, so the failure mode here is visible rather than hidden, unlike the situation on a 44-residue chain.
A certificate that reports observed mass against calculated mass therefore closes most of the risk on this compound, provided the calculated figure is for the correct construct.
What Do the D-Residues Contribute?
Two residues in ipamorelin peptide are in the D-configuration and that is a deliberate design decision rather than a synthesis artefact.
Proteases evolved against L-amino acids, which is what ribosomes produce and what natural proteins are made of. A D-residue presents the wrong spatial arrangement to a protease active site.
The enzyme can still bind the region but cannot orient the scissile bond correctly, so cleavage rates drop sharply.
Placing D-residues at positions a protease would otherwise target is the standard route to extending the useful life of a short peptide, and it costs nothing at the receptor if the receptor tolerates the change.
That last condition is not automatic. A D-substitution flips the side chain to the opposite face, and for many binding sites that abolishes activity.
For ipamorelin peptide it did not, which is a finding rather than an assumption, and it is why the molecule works at all in the configuration it has.
For a laboratory the practical consequence is that the compound survives longer in a preparation containing serum or tissue homogenate than an all-L peptide of the same length would.
Verification of configuration is a separate question from verification of mass, since a D-residue and its L-counterpart weigh exactly the same. Chiral analysis is the only method that distinguishes them and most certificates do not include it.
One practical note on how to ask about this. A supplier asked whether the configurations were verified will usually say the synthesis used the correct protected building blocks, which is a statement about inputs rather than about the product.
That answer is not worthless. Chiral building blocks are what determine the configuration, and racemisation during coupling is the failure it does not rule out.
Ipamorelin peptide is short enough that this risk is small, and knowing which question was answered is still better than assuming.
What Should an Ipamorelin Certificate Show?
Six fields cover ipamorelin peptide, and one of them is specific to any peptide containing non-coded residues.
Observed mass against calculated mass. At 712 daltons any deletion is a large proportional change, so this single figure carries more weight here than on a long peptide.
Purity by reverse-phase HPLC with the chromatogram supplied. Look for peaks eluting close to the main peak, since those are the deletion sequences and a summary percentage hides them.
The full construct written out including the non-coded residues and their configurations, because a name does not specify which positions are D and which are L.
Whether the carboxy terminus is amidated. The free acid has a different mass and different activity and it is a routine synthesis failure.
Counterion identity together with net peptide content. A basic lysine on a 712 dalton backbone gives a proportionally larger trifluoroacetate share than any long peptide carries, commonly near twenty percent.
Lot number and synthesis date.
A certificate omitting the amidation status is the most common gap on this compound, and it is the one that changes the molecule most for the least visible reason.
A note on reading the chromatogram rather than the number attached to it. Purity by area percent assumes every species present absorbs at the detection wavelength in proportion to its quantity.
For deletion sequences of the same peptide that assumption is close to true. For a non-peptide contaminant it can be badly wrong, since something that does not absorb at 214 nanometres contributes nothing to the area and still occupies mass in the vial.
What Is Unusual About the Receptor?
GHS-R1a has a property that is easy to overlook and that shapes how any experiment on it should be designed.
It is constitutively active. The receptor produces substantial signalling in the absence of any ligand, reported in the region of half its maximal activity in several published systems.
Most G-protein coupled receptors sit near silent until something binds them. This one does not.
The consequence is that a baseline measurement in a GHS-R1a system is not a zero. It is a raised starting point, and a compound added to that system is modulating an active receptor rather than switching on an inactive one.
That changes what a control means. An untreated well is not an unstimulated well, and the difference between them is the constitutive signal.
It also creates a category of compound that has no equivalent in a silent receptor system. An inverse agonist reduces signalling below the unliganded baseline, which is only a coherent idea where an unliganded baseline exists to fall below.
Ipamorelin peptide is an agonist rather than an inverse agonist, and the point here is what the assay reports rather than what the compound does.
A response expressed as fold-change over baseline compresses differently in a constitutively active system than in a silent one, so two laboratories quoting fold-change can disagree while measuring the same thing.
Reporting absolute signal alongside fold-change resolves it. That is a small change to a results table and it removes an argument that otherwise recurs.
The receptor was cloned in 1996 and its natural ligand was identified three years later, so this property was characterised well before the ligand was known.
How Stable Is It Once Reconstituted?
This compound is unusually well behaved in solution, and the reason is what the sequence does not contain.
There is no methionine, so there is no oxidation-sensitive side chain of the kind that limits most peptides in this catalogue.
There is no asparagine or glutamine, so deamidation has nothing to act on.
There is no cysteine, so there is no disulfide to scramble and no free thiol to oxidise.
There is no aspartate-glycine motif, so the isomerisation route that quietly ruins bioregulator solutions is absent.
What remains is a short, amidated, partly D-configured chain with no chemically labile side chain at all, which is close to the best case for aqueous stability in a synthetic peptide.
That does not make a reconstituted solution indefinitely usable, and the limits are physical and microbiological rather than chemical.
Adsorption removes peptide from dilute solutions into container walls, which is a loss of concentration rather than a change in the molecule, and it is worst at the lowest working dilutions.
Microbial growth is the other limit. Bacteriostatic diluent addresses it and plain water does not, and a solution held at 4 degrees Celsius in unpreserved water is a growth medium with a peptide in it.
So the honest storage answer for ipamorelin peptide is that chemistry is rarely what ends a solution here. Handling and contamination are, and both are controllable.
How Should the Vial Be Handled?
Ipamorelin peptide is more forgiving than most of the catalogue, within limits, being short and amidated.
Sealed dry powder holds at refrigeration temperature for short periods and at minus 20 for extended storage, with light excluded throughout.
Bring the vial to room temperature before opening. The powder is hygroscopic and cold glass condenses atmospheric moisture immediately.
A 10 mg vial of a 712 dalton peptide contains a large molar quantity, which is the practical argument for this size over the smaller one when a study runs several arms.
Reconstitute by adding diluent down the wall and swirling. Five residues aggregate less readily than forty-four and the habit is worth keeping regardless.
Aliquot on first reconstitution. The molar quantity in a 10 mg vial makes repeated freeze-thaw of the whole volume wasteful as well as damaging.
Use low-binding consumables at working dilutions, since adsorption removes a fraction of any dilute peptide from small-volume plastics.
Record lot, net peptide content, diluent volume and date of first reconstitution, which is the minimum set another laboratory needs to reproduce the preparation.
Published Literature
Selected references on the characterisation of this compound and on the receptor it acts through.
- Raun K, Hansen BS, Johansen NL, Thogersen H, Madsen K, Ankersen M, et al. European Journal of Endocrinology. 1998;139(5):552-561. DOI: 10.1530/eje.0.1390552
- Howard AD, Feighner SD, Cully DF, Arena JP, Liberator PA, Rosenblum CI, et al. Science. 1996;273(5277):974-977. DOI: 10.1126/science.273.5277.974
- Kojima M, Hosoda H, Date Y, Nakazato M, Matsuo H, Kangawa K. Nature. 1999;402(6762):656-660. DOI: 10.1038/45230
- Holst B, Cygankiewicz A, Jensen TH, Ankersen M, Schwartz TW. Molecular Endocrinology. 2003;17(11):2201-2210. DOI: 10.1210/me.2003-0069
Frequently Asked Questions
What is ipamorelin peptide?
A five-residue growth hormone secretagogue acting at GHS-R1a, calculated at approximately 711.9 daltons for the free base, carrying an amidated carboxy terminus.
What did the 1998 selectivity finding measure?
Other pituitary outputs alongside growth hormone, including adrenocorticotropic hormone, cortisol and prolactin, compared against reference secretagogues in the same experimental system.
Why does measuring the other outputs matter?
Because a compound tested only for the effect it was designed to produce cannot generate evidence of selectivity. Nothing was measured that could have contradicted the claim.
How broad is that finding?
Narrower than it is usually repeated. It establishes a separation across a measured concentration range in a defined preparation, not a property that holds at any concentration or in any species.
Which residues are not standard amino acids?
Two. An alpha-aminoisobutyric acid residue and a naphthylalanine residue, neither of which is encoded by the genetic code.
Why does that complicate synthesis?
Both are sterically bulky, which slows the coupling step that follows them. A slow coupling is an incomplete one, and the chains that failed to react appear as deletion sequences.
Is that failure easy to detect?
Yes, on this molecule. At 712 daltons a single deletion is roughly ten to fifteen percent of total mass, which is unmissable on any mass spectrometer. Short chains make this failure visible.
What do the D-configuration residues do?
They resist proteases. Enzymes evolved against L-amino acids and cannot orient the scissile bond correctly when a D-residue is present, so cleavage rates drop sharply.
Can a certificate confirm the configurations?
Not by mass. A D-residue and its L-counterpart weigh exactly the same, so chiral analysis is the only method that distinguishes them, and most certificates do not include it.
What is the most common certificate gap here?
Amidation status of the carboxy terminus. The free acid has a different mass and different activity, it is a routine synthesis failure, and many certificates do not state which form was made.
How large is the counterion correction?
Proportionally larger than on a long peptide because the molecule is only 712 daltons and carries a basic lysine. Commonly in the region of twenty percent once water and residual salt are counted.
When does the 10mg vial make sense over 5mg?
When a study runs several arms or repeats. A 10 mg vial of a 712 dalton peptide contains a large molar quantity, and the cost per unit is lower than buying two smaller vials.
Compliance Statement
Ipamorelin peptide is sold exclusively for laboratory research use. It is not a drug, food, or cosmetic product, and it is not a dietary product of any kind. It is not approved by the FDA or any comparable authority for human or veterinary use, the 1998 selectivity finding describes a separation measured across a defined concentration range in a specific experimental preparation and does not establish a property that holds at any concentration or in any species, and no compound in this range is offered for any human or veterinary purpose. This product is not intended to diagnose, treat, cure, or prevent any disease. It must not be given to humans or animals. Purchase is restricted to qualified researchers and institutions operating within applicable laws. All handling is the responsibility of the purchasing laboratory.
Other formats of Ipamorelin
Ipamorelin is also stocked as Ipamorelin 10mg Nasal Spray, Ipamorelin 5mg, CJC-1295 (no DAC), Ipamorelin 10mg (Blend), CJC-1295 (No DAC) + Ipamorelin 15mg preloaded 3ml pen, CJC-1295 (NO DAC) 5MG and CJC-1295 (NO DAC) 10MG. Each listing states its own quantity and concentration, and the pen and vial comparison explains what changes between formats.
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