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Molecular Weight
Purity
Storage
Appearance
Solubility
01
GHRP-2 (growth hormone-releasing peptide-2, also called pralmorelin) is a synthetic six-residue peptide that activates the growth hormone secretagogue receptor (GHS-R1a), the ghrelin receptor. It came out of systematic structure–activity work on small secretagogue peptides and is one of the most potent members of the GHRP family in receptor assays.
Its sequence, D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH₂, contains three D-amino acids and the non-proteinogenic residue 2-naphthylalanine, together with tryptophan. This aromatic-rich, protease-resistant structure makes GHRP-2 a standard comparison compound for other ghrelin-receptor ligands and a useful test case in analytical method development. It is supplied as a lyophilized reference material for in vitro research only.
02
GHRP-2 alternates D- and L-residues around three aromatic side chains, which together define how it fits the receptor.
D-Ala, position 1
A D-configured N-terminal residue that protects against aminopeptidases.
D-2-Nal, position 2
A bulky naphthalene ring presented in the D-configuration. It occupies a key hydrophobic pocket in the receptor and contributes strong UV absorbance.
Trp, position 4
The indole ring adds a second aromatic contact point and gives the peptide natural fluorescence.
D-Phe, position 5
A third aromatic group, D-configured, which helps hold the aromatic residues in the arrangement the receptor recognises and resists endopeptidases.
Lys-NH₂, position 6
The C-terminal lysine adds a positive charge, and the amide end protects against carboxypeptidases.
Compared with Ipamorelin, GHRP-2 is one residue longer, contains tryptophan, and has D-Ala in place of Aib at the N-terminus.
03
GHRP-2 is used as a reference agonist in in vitro studies of the ghrelin receptor.
Receptor binding
Competition binding assays with radiolabelled ghrelin in GHS-R1a-expressing membranes measure its affinity, which is typically high, and compare it across the GHRP series.
Signalling
GHS-R1a signals mainly through Gq, so intracellular calcium release and inositol phosphate accumulation are the usual functional readouts.
Selectivity
Published studies describe GHRP-2 as less selective than Ipamorelin: in experimental models it raised ACTH/cortisol and prolactin as well as growth hormone. This makes the pair a common contrast in selectivity research.
All research context described here refers to controlled in vitro and preclinical experimental systems.
04
Potency benchmark
A standard comparator in GHS-R1a binding and signalling panels alongside ghrelin, GHRP-6 and Ipamorelin.
Fluorescence-based methods
The tryptophan residue allows fluorimetric detection, useful when developing sensitive quantification methods.
Aromatic peptide chromatography
Its three aromatic residues give strong retention and UV response, making it a good test compound for column selectivity studies.
Chiral analysis
With three D-residues to confirm, it is a practical standard for validating chiral amino acid analysis.
05
Storage
Store the lyophilized powder at −20 °C, sealed, desiccated and protected from light. Let the vial reach room temperature before opening.
Light sensitivity
Tryptophan can photo-oxidise to kynurenine-type products. Handle under subdued light and use amber or opaque containers.
Enzymatic stability
The three D-residues make the peptide resistant to most common proteases in in vitro media.
Chemical stability
There is no methionine, cysteine or asparagine, so tryptophan oxidation is the main chemical degradation route.
Reconstitution
Dissolve in water or dilute acetic acid; DMSO stocks diluted into buffer are also common for cell assays. Its hydrophobic character makes low-binding polypropylene labware advisable.
06
The aromatic residues give GHRP-2 distinctive and convenient analytical signatures.
HPLC
Retains strongly on reversed-phase C18 columns. Detection at 214 nm gives general sensitivity, while 280 nm is selective for the aromatic residues.
Mass spectrometry
ESI-MS in positive mode shows [M+H]⁺ at m/z 818.4 and [M+2H]²⁺ at m/z 409.7. In MS/MS, immonium ions at m/z 159.1 (Trp), 170.1 (2-Nal) and 120.1 (Phe) support sequence confirmation.
Fluorescence
Excitation near 280 nm and emission near 340 nm allow sensitive detection of the tryptophan-containing peptide.
Stereochemistry
After acid hydrolysis, Marfey’s reagent derivatisation or chiral chromatography confirms the D-configuration at positions 1, 2 and 5; L-epimers formed during synthesis are the main stereochemical impurity.
Impurity profile
Typical checks also cover tryptophan oxidation products, truncated sequences and the non-amidated free acid.
07
GHRP-2 is a six-residue peptide containing tryptophan and D-Ala at its N-terminus, while Ipamorelin has five residues and starts with Aib. In experimental models GHRP-2 is generally more potent but less selective, also raising ACTH/cortisol and prolactin.
Three: D-alanine at position 1, D-2-naphthylalanine at position 2 and D-phenylalanine at position 5. Ala3, Trp4 and Lys6 are L-configured.
Its tryptophan residue can photo-oxidise to kynurenine-type products, which appear as impurities in HPLC and MS. Storing it in amber or opaque containers and handling it under subdued light limits this.
[M+H]⁺ at m/z 818.4 and [M+2H]²⁺ at m/z 409.7, with MS/MS immonium ions at m/z 159.1 (Trp), 170.1 (2-Nal) and 120.1 (Phe).
No. It is supplied strictly as a reference compound for laboratory and analytical research and is not for human or animal use.
GHRP-2 Research Reference. (2026). Pure Peptides Labs Research Catalogue. Retrieved from https://purepeptideslabs.net/research-catalogue/growth-hormone-axis-research-peptides/ghrp-2/
Materials listed on this platform are supported by independent testing and published documentation for laboratory research contexts.
