GHRP-2 Specs: Sequence, MW & CAS
Part of the full GHRP-2 guide - a synthetic hexapeptide growth hormone secretagogue reference compound, identity-verified with a COA on every vial.
In brief
GHRP-2's molecular specification is unusually informative because nearly every field on the spec card maps to a functional design choice. The free peptide carries the molecular formula C45H55N9O6, an average molecular weight of 817.99 g/mol, CAS Registry Number 158861-67-7, and the sequence D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2. It is classified as a synthetic hexapeptide growth hormone secretagogue and ghrelin-receptor (GHS-R1a) agonist, and it is known in the literature as pralmorelin, marketed in Japan as a diagnostic agent (GHRP Kaken 100). This section reads each specification not as an isolated number but as a structure-function clue: how the six residues, the non-natural building blocks, the molecular weight, and the registry identity together explain why this compact peptide behaves as a potent receptor agonist in the in-vitro systems where it has been studied.
To the molecule
Molecular specifications
D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2 (D-Ala-D-beta-(2-naphthyl)-Ala-Ala-Trp-D-Phe-Lys-amide)The detail
A closer look
01
Reading the sequence: a designed hexapeptide
The sequence D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2 (equivalently D-Ala-D-beta-(2-naphthyl)-Ala-Ala-Trp-D-Phe-Lys-amide) is six residues long, defining GHRP-2 as a hexapeptide. Three positions use D-configured or non-natural residues: D-alanine, D-2-naphthylalanine, and D-phenylalanine, while the C-terminus is amidated (NH2) rather than a free acid. This is not a natural peptide sequence but an engineered ghrelin mimetic. The bulky aromatic D-2-naphthylalanine and the aromatic Trp and D-Phe residues provide the hydrophobic, ring-rich character that suits the conserved ligand-activation domain of GHS-R1a, while the lysine contributes a basic side chain. The deliberate use of non-proteinogenic residues is the structural signature of a synthetic secretagogue.
02
Molecular weight and formula in context
The molecular formula C45H55N9O6 corresponds to an average molecular weight of 817.99 g/mol for the free peptide base (Wikipedia lists 817.992 g/mol). For a six-residue peptide this is consistent with the presence of bulky aromatic side chains such as the naphthylalanine, which add carbon and mass beyond what a simple all-alanine hexapeptide would weigh. The nine nitrogen atoms reflect the peptide backbone amides, the C-terminal amide, the tryptophan indole, and the lysine side-chain amine. Practically, the 817.99 g/mol figure is the conversion constant a researcher uses to translate a weighed mass into molar concentration for receptor-binding and signaling assays, making the molecular weight the single most operationally important spec on the card.
03
Identity fields: CAS, class, and synonyms
CAS Registry Number 158861-67-7 uniquely identifies the free peptide base of GHRP-2 across chemical databases, the unambiguous handle for sourcing and verification independent of naming variation. The compound's drug-class designation is a synthetic growth hormone secretagogue hexapeptide and GHS-R1a (ghrelin receptor) agonist. Its principal synonym is pralmorelin, and it is noted as having been marketed in Japan as a diagnostic agent under the designation GHRP Kaken 100. These identity fields matter because the same molecule appears in the literature under multiple names; recognizing that GHRP-2 and pralmorelin are the same CAS 158861-67-7 entity lets a researcher correctly assemble the structure-activity and pharmacology record that the cited sources provide.
The fine print: products are sold for laboratory research use only and are not for human or animal consumption. Bodily introduction into humans or animals is strictly prohibited by law. GHRP-2 is not a drug and is not intended to diagnose, treat, cure, or prevent any disease. These statements have not been evaluated by the FDA.