What Is Sermorelin? GRF(1-29) Research Overview

If you've searched "what is sermorelin acetate," the short answer is: the first 29 amino acids of human growth-hormone-releasing hormone (GHRH), with an amidated C-terminus, supplied as an acetate salt. Sermorelin, also written GRF(1-29)NH2 or simply GRF 1-29, is the shortest fragment of GHRH that keeps the full hormone's activity at the GHRH receptor. That is why it is studied as a compact, native-sequence model of GHRH signaling. This research-use-only overview covers what the molecule is, what the "acetate" refers to, and how it compares with full-length GHRH, tesamorelin and CJC-1295.

What is sermorelin acetate?

Sermorelin is a synthetic 29-residue peptide identical in sequence to residues 1–29 of human GHRH, the hypothalamic hormone that signals pituitary somatotrophs to release growth hormone. Native GHRH is 44 amino acids long, but structure–activity work established that the N-terminal 29 residues are enough to bind and activate the GHRH receptor. Sermorelin is that minimal active fragment, with the C-terminal carboxyl group replaced by an amide (the "NH2" in GRF(1-29)NH2), mirroring the amidated C-terminus of the native hormone.

Sermorelin acetate sequence, structure and molecular weight

In one-letter code, the sermorelin sequence is YADAIFTNSYRKVLGQLSARKLLQDIMSR-NH2, running from tyrosine at position 1 to arginine at position 29. The free peptide has the molecular formula C149H246N44O42S and a molecular weight of roughly 3,358 g/mol; the single sulfur atom comes from the methionine at position 27. The acetate salt adds the mass of its counter-ions, so listings for the salt form can show a higher weight. Sermorelin is indexed under CAS registry number 86168-78-7, and salt forms can carry their own registry entries, so a CAS number should always be read alongside the form it refers to.

Sermorelin acetate vs sermorelin

"Sermorelin acetate vs sermorelin" is a naming question rather than a chemistry one. Peptides are isolated and lyophilized as salts, with counter-ions balancing their charged groups, and sermorelin carries several basic residues (arginine and lysine) that pair with acetate. Sermorelin acetate is simply sermorelin in its acetate salt form. The amino-acid sequence, the receptor target and the mechanism are identical; the label tells you which counter-ion accompanies the peptide. Sermorelin acetate from Eon Research is supplied in this form.

What does sermorelin acetate do at the GHRH receptor?

Sermorelin acts where native GHRH acts: the GHRH receptor (GHRH-R), a class B G-protein-coupled receptor on anterior-pituitary somatotrophs. Binding activates Gs signaling, which raises cyclic AMP and engages protein kinase A. In somatotroph models that cascade does two things researchers measure separately. Over minutes it stimulates release of stored growth hormone; over longer time frames it supports GH gene transcription and somatotroph proliferation.

Because sermorelin works through the endogenous receptor, its signal stays subject to the system's own brakes: hypothalamic somatostatin opposes GHRH-receptor signaling, and IGF-1 feeds back to restrain GH secretion.

What is sermorelin acetate used for in research?

In the laboratory, sermorelin serves as a reference GHRH-receptor agonist. Common in-vitro and animal-model research themes include:

• GHRH-receptor binding and cAMP/PKA signaling in pituitary cell models
• Somatotroph GH release and GH gene expression
• The interplay between GHRH-receptor input and somatostatin tone
• Combined GHRH- and ghrelin-receptor signaling alongside a GHS-R1a agonist such as ipamorelin
• Structure–activity comparisons against stabilized GHRH analogs
• Enzymatic stability of GHRH fragments, particularly DPP-4 cleavage

Sermorelin acetate half-life and stability

Sermorelin's half-life is short, measured in minutes in reported models, and the reason is structural. Because it keeps the native N-terminus, it is a substrate for dipeptidyl peptidase-4 (DPP-4), which clips the tyrosine-alanine pair from positions 1 and 2. The resulting fragment, GRF(3-29), has sharply reduced activity at the receptor. The practical consequence for study design is a brief, time-locked GHRH input: well suited to modeling a single native-like pulse, less suited to holding a GHRH signal steady over hours. Every stabilized analog below exists, in large part, to solve this problem.

Sermorelin vs full-length GHRH

Native human GHRH is a 44-residue amidated peptide; sermorelin is its first 29 residues. Both bind and activate the same receptor, and both are DPP-4 substrates because they share the same N-terminal sequence. The shorter fragment is simpler to synthesize and handle, which is why GRF(1-29)NH2 became the standard research form of the hormone and the backbone from which most later GHRH analogs were built.

Sermorelin vs tesamorelin

Tesamorelin takes the opposite route to stability. Rather than shortening GHRH, it keeps all 44 residues and attaches a trans-3-hexenoyl group to the N-terminal tyrosine, a cap studied for protecting the peptide from DPP-4 cleavage. Sermorelin is the minimal native fragment; tesamorelin is the full-length hormone with a protective modification. Both are GHRH-receptor agonists, and they differ in length and enzymatic stability rather than in target. For more on the full-length analog, see What Is Tesamorelin?.

GRF 1-29 vs CJC-1295 (and mod GRF 1-29)

This is where the naming causes the most confusion. GRF 1-29 is sermorelin. Modified GRF 1-29, also called CJC-1295 without DAC, is GRF(1-29) with four amino-acid substitutions at positions 2, 8, 15 and 27 that improve resistance to enzymatic cleavage and chemical degradation, lengthening its half-life from minutes to roughly half an hour in reported models. All of them share the GRF(1-29) backbone and the same receptor: a ladder of increasing stability built on one sequence.

• Sermorelin (GRF 1-29): native sequence, DPP-4-labile, half-life in minutes
• Modified GRF 1-29 (CJC-1295 no-DAC): four stabilizing substitutions, roughly 30 minutes in reported models
• CJC-1295 DAC: albumin-binding DAC, roughly 6–8 days in reported models
• Tesamorelin: full-length GHRH(1-44) with an N-terminal trans-3-hexenoyl group

For the full side-by-side of the two GRF(1-29)-based analogs, see Sermorelin vs CJC-1295.

Sermorelin acetate vs HGH

Sermorelin is often compared with HGH, but the two sit at different levels of the axis. Recombinant human growth hormone is the 191-amino-acid hormone itself, acting directly on GH receptors in peripheral tissues. Sermorelin is a 29-residue releasing factor that acts one step upstream at the pituitary, prompting somatotrophs to release their own GH. A GHRH-receptor agonist therefore depends on a responsive pituitary and remains under somatostatin and IGF-1 feedback, while exogenous GH bypasses that regulation entirely.

Sermorelin vs ipamorelin: different receptors

Sermorelin is a GHRH analog acting at GHRH-R; ipamorelin is a ghrelin-receptor (GHS-R1a) agonist. The two pathways converge on GH release through different second messengers, which is why GHRH-side and ghrelin-side compounds are studied as complements rather than substitutes, as covered in Ipamorelin vs Tesamorelin and the CJC-1295 + ipamorelin stack. For the ghrelin side alone, see What Is Ipamorelin?.

Handling and reconstitution

Sermorelin acetate ships lyophilized and is reconstituted with bacteriostatic water before in-vitro use. The sermorelin reconstitution calculator converts vial size and diluent volume into concentration and aliquot volume, and our guide on how to reconstitute peptides covers bench technique. Every sermorelin lot from Eon Research ships lyophilized in multi-vial research kits from our US facility within 48 hours with tracking.