Sermorelin Molecular Weight, Sequence & CAS Reference
Sermorelin is a synthetic 29-amino acid peptide corresponding to the N-terminal catalytic domain of endogenous growth hormone-releasing hormone (GHRH). This reference sheet outlines the complete primary sequence, chemical formula, exact molecular weight, CAS registry details, salt counterion impacts, and analytical testing standards required for high-precision laboratory assays. All data provided are strictly intended to support non-clinical, in vitro, and preclinical investigative research.
Quick answer
Sermorelin is a synthetic 29-amino acid peptide corresponding to the N-terminal catalytic domain of endogenous growth hormone-releasing hormone (GHRH). This reference sheet outlines the complete primary sequence, chemical formula, exact molecular weight, CAS registry details, salt counterion impacts, and analytical testing standards required for high-precision laboratory assays. All data provided are strictly intended to support non-clinical, in vitro, and preclinical investigative research.
Key takeaways
- [Sermorelin](/research-peptides/sermorelin) represents the fully active, truncated N-terminal sequence of native human growth hormone-releasing hormone (GHRH 1-44).
- Determining exact stoichiometry is essential for preparing accurate molar solutions in quantitative research applications.
- Lyophilized research peptides are rarely isolated as pure neutral free bases.
- To understand molecular structure-activity relationships, laboratory researchers frequently compare [Sermorelin](/research-peptides/sermorelin) against other synthetic GHRH receptor ligands and secretagogues.
Primary Structure and Amino Acid Sequence
Sermorelin represents the fully active, truncated N-terminal sequence of native human growth hormone-releasing hormone (GHRH 1-44). Comprising 29 amino acids, this peptide retains complete bioactivity with respect to receptor activation while presenting a lower total molecular mass than the full-length hormone. The primary sequence is defined as follows using standard single-letter amino acid code: YADAIFTNSYRKVLGLSARKLLQDIMSR-NH2.
In the three-letter amino acid notation, the structural arrangement is written as: H-Tyr-Ala-Asp-Ala-Ile-Phe-Thr-Asn-Ser-Tyr-Arg-Lys-Val-Leu-Gly-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Met-Ser-Arg-NH2. The C-terminal residue (Arginine) features an amide modification (-NH2) rather than a free carboxyl group (-COOH). This C-terminal amidation enhances peptide stability against exopeptidase degradation in experimental media, mimicking the natural modification found in full-length secretagogues.
Researchers evaluating structural biology or signaling cascades can examine our reference standards across all peptides supplied by PX1 Research. Maintaining sequence fidelity is critical when mapping ligand-binding interactions at the GHRH receptor surface during cell-based assays.
Chemical Formula, Molecular Mass, and CAS Registration
Determining exact stoichiometry is essential for preparing accurate molar solutions in quantitative research applications. Sermorelin possesses a chemical formula of C149H246N44O42S, reflecting its precise atomic composition including 149 carbon atoms, 246 hydrogen atoms, 44 nitrogen atoms, 42 oxygen atoms, and 1 sulfur atom attributable to the single Methionine residue at position 27.
The monoisotopic mass of free-base Sermorelin is approximately 3355.82 Da, while the average molecular weight based on standard atomic weights is calculated at 3357.88 g/mol. Depending on the synthetic route, purification protocols, and counterion equilibration, small variations in measured mass via mass spectrometry reflect salt forms rather than altered backbone identity.
Sermorelin acetate is formally registered in chemical databases under the Chemical Abstracts Service CAS registry number 86168-78-7 (or 114466-38-5 for specific salt formulations). For laboratory inventory management, high-purity Sermorelin is synthesized using solid-phase peptide synthesis (SPPS) protocols to enforce exact molecular mass compliance.
Salt Forms, Counterions, and Net Peptide Content Dynamics
Lyophilized research peptides are rarely isolated as pure neutral free bases. During reverse-phase high-performance liquid chromatography (RP-HPLC) purification and subsequent lyophilization, basic amino acid residues—such as the Lysine and Arginine side chains present in Sermorelin—form ionic complexes with atmospheric or solvent-derived counterions. The most common salt forms for research peptides are acetate (CH3COO-) and trifluoroacetate (CF3COO-).
The presence of salt counterions and residual bound moisture directly influences total gross mass measurements. Net Peptide Content (NPC) defines the actual weight percentage of the peptide sequence relative to the total mass of the powder, which includes counterions and bound water. For Sermorelin acetate standard lots, typical NPC ranges from 78% to 88%. The remaining 12% to 22% of gross product weight consists of acetate counterions and trace hydration balance.
When preparing controlled micromolar or nanomolar concentrations for in vitro assays, researchers must account for NPC rather than assuming 100% gross weight efficiency. For instance, weighing out 1.0 mg of lyophilized powder with an 80% NPC yields 0.80 mg of pure Sermorelin peptide sequence. Detailed analytical metrics describing counterion composition are always provided in the lot-specific COA supplied with PX1 Research compounds.
Comparative Structural Metrics Across GHRH Class Compounds
To understand molecular structure-activity relationships, laboratory researchers frequently compare Sermorelin against other synthetic GHRH receptor ligands and secretagogues. Differences in amino acid length, D-amino acid substitutions, lipid conjugation, or counterion chemistry produce distinct chemical profiles, enzymatic half-lives, and solubility characteristics in buffer systems.
For instance, structural comparisons with Tesamorelin reveal that while Sermorelin contains 29 amino acids, Tesamorelin incorporates the same 44-amino acid sequence as native GHRH attached to a hexenoyl moiety at its N-terminus, resulting in a significantly higher molecular weight of approximately 5135.9 g/mol. Similarly, CJC-1295 utilizes tetrasubstituted amino acid modifications (D-Ala, Gln, Ala, Leu substitutions) to resist dipeptidyl peptidase-4 (DPP-IV) cleavage, altering its molecular mass and charge profile relative to unmodified Sermorelin. Non-GHRH secretagogues like Ipamorelin operate via the ghrelin/growth hormone secretagogue receptor (GHS-R) rather than the GHRH receptor and feature a compact pentapeptide structure (MW: 711.86 g/mol).
Evaluating these structural parameters allows comparative investigation into receptor selectivity, binding affinity ($K_d$), and downstream signal transduction mechanisms in cellular culture models.
Physical Properties and In Vitro Solubilization Protocols
Sermorelin is supplied as a sterile, lyophilized white-to-off-white powder engineered for high physical stability during transport and storage. As a basic peptide containing multiple polar and positively charged amino acid residues (Arg, Lys, His absent, Asp acidic), Sermorelin exhibits robust solubility in aqueous buffer systems, including sterile water for injection, bacteriostatic water, and phosphate-buffered saline (PBS, pH 7.4).
To solubilize lyophilized Sermorelin, solvents should be introduced gently along the glass vial wall rather than sprayed directly onto the peptide cake. Gentle swirl mixing is recommended; vigorous vortexing or sonic agitation must be avoided as mechanical shear forces can induce peptide aggregation, surface denaturation, or secondary structure disruption.
For accurate volumetric calculations when preparing laboratory stock solutions, investigators are encouraged to utilize our interactive reconstitution calculator. This tool streamlines mass-to-volume conversions based on targeted concentration goals and specific vial mass allotments.
Analytical Validation: HPLC, Mass Spectrometry, and Endotoxin Testing
Rigorous analytical quality control is mandatory to confirm that research compounds match theoretical structural parameters without cross-contamination or synthetic truncated impurities. PX1 Research subjects every production lot of Sermorelin to comprehensive third-party testing within ISO 17025 accredited analytical laboratories.
Purity is assessed using analytical High-Performance Liquid Chromatography (RP-HPLC). A sharp, single chromatographic peak indicates the absence of synthetic deletion sequences or oxidation products, with a strict purity threshold of ≥98.0%. Identity verification is conducted via Electrospray Ionization Mass Spectrometry (ESI-MS) or Matrix-Assisted Laser Desorption/Ionization (MALDI-TOF), verifying the observed molecular mass matches the theoretical mass of 3357.88 g/mol within defined instrumentation error tolerances (±0.5 Da).
In addition to identity and purity verification, preclinical cell culture and tissue assays require strict control over bacterial contamination. PX1 Research enforces rigorous endotoxin testing via Chromogenic Limulus Amebocyte Lysate (LAL) assays, ensuring endotoxin levels remain below safe thresholds (<0.05 EU/mg). Full documentation is publicly accessible through our central research database and product COA lookup.
Receptor Binding Mechanism and Signal Transduction in Cell Models
In vitro functional assays demonstrate that Sermorelin acts as a selective agonist at the growth hormone-releasing hormone receptor (GHRHR), a class B G-protein coupled receptor expressed primarily on pituitary somatotropes and select peripheral tissue cell lines. Upon ligand binding to the extracellular domain of GHRHR, a conformational change triggers heterotrimeric $G_{\alpha s}$ protein coupling.
Preclinical studies indicate that $G_{\alpha s}$ activation stimulates membrane-bound adenylyl cyclase, driving the intracellular conversion of adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP). Elevated cAMP concentrations activate Protein Kinase A (PKA), which phosphorylates the cAMP-response element-binding protein (CREB). CREB translocation to the nucleus promotes transcript expression of growth hormone (GH) genes.
Furthermore, GHRHR activation initiates secondary signaling pathways including the phospholipase C (PLC) / inositol trisphosphate ($IP_3$) / intracellular calcium ($Ca^{2+}$) cascade. In vitro cell culture models utilize these signal transduction markers to quantify relative peptide potency, EC50 values, and receptor desensitization kinetics over extended incubation periods.
Laboratory Storage, Stability, and Handling Guidelines
Proper storage conditions must be maintained to protect Sermorelin from chemical degradation pathways such as oxidation (particularly at the Met27 residue), deamidation (at Asn8 and Gln16/25), and peptide bond hydrolysis. Lyophilized Sermorelin should be stored at -20°C to -80°C in a desiccated environment away from direct light exposure for long-term stability.
Under controlled freezer storage (-20°C), intact lyophilized vials remain stable for up to 24 months. Upon reconstitution with appropriate solvent (e.g., bacteriostatic water or sterile buffered saline containing 0.9% benzyl alcohol), liquid stock solutions should be stored at 2°C to 8°C and utilized within 28 days to prevent gradual degradation or bacterial proliferation.
For bulk experimental protocols or institutional inquiries regarding scaled research quantities, institutional buyers can review specialized options through our wholesale laboratory access portal. All shipments originate from our CA or AZ fulfillment facilities with same-day dispatch for orders confirmed Monday through Friday before cut-off times.
Frequently Asked Questions
What is the primary sequence of Sermorelin?
Sermorelin consists of 29 amino acids with the primary sequence: Tyr-Ala-Asp-Ala-Ile-Phe-Thr-Asn-Ser-Tyr-Arg-Lys-Val-Leu-Gly-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Met-Ser-Arg-NH2. It features a C-terminal amide group.
What is the molecular weight and formula of Sermorelin?
Sermorelin has a chemical formula of C149H246N44O42S and an average molecular weight of approximately 3357.88 g/mol (monoisotopic mass ~3355.82 Da).
What is the CAS registry number for Sermorelin?
The CAS registry number assigned to Sermorelin acetate is 86168-78-7 (also referenced under 114466-38-5 for specific salt hydrates).
How does Net Peptide Content (NPC) affect experimental calculations?
Lyophilized peptide samples contain bound counterions (acetate or TFA) and moisture. An NPC of 80% means that in a 1.0 mg measured sample of powder, 0.80 mg is active peptide sequence and 0.20 mg consists of counterions and moisture. Molar concentrations must be calculated using the net peptide mass.
How does Sermorelin differ structurally from full-length GHRH?
Native human GHRH contains 44 amino acids. Sermorelin comprises only the first 29 N-terminal amino acids (GHRH 1-29 amide), retaining full biological activity at the receptor while reducing total molecular mass.
What purity levels are confirmed on the PX1 Research COA?
Every lot of Sermorelin manufactured for PX1 Research is verified via analytical RP-HPLC to ensure a minimum sequence purity of ≥98.0%, with identity verified by mass spectrometry and endotoxin levels tested below <0.05 EU/mg.
How should reconstituted Sermorelin solutions be handled in the lab?
Reconstituted stock solutions should be refrigerated at 2°C to 8°C and protected from light. Repeated freeze-thaw cycles of liquid aliquots should be avoided to prevent mechanical shearing and aggregation.
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