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Identity And Molecular Context — Deep Dive

By Editorial Desk · published 2026-05-01 · last reviewed 2026-05-25 · Guide

If you have been reading about lipogenesis and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.

Updated 2026-05-25. Numbers and descriptions here follow the published literature rather than marketing material.

Identity and Molecular Context

AOD-9604 is a synthetic peptide modeled on the C-terminal region of human growth hormone. It corresponds to residues 176-191 of the 191-amino-acid hGH sequence. The fragment is not the full hormone and lacks the receptor-binding region associated with growth and metabolic effects of hGH. Researchers developed it to isolate a specific portion of hGH for study. Its exact sequence and length are often stated in peptide catalogs and patents.

The peptide is frequently described as a growth hormone fragment, although it is chemically distinct from full-length hGH. AOD-9604 contains 16 amino acids and includes two cysteine residues that can form an intramolecular disulfide bond. In solution, this structural feature can influence folding, aggregation, and stability. Published descriptions sometimes call it hGH 176-191 or AOD9604, with spacing and capitalization varying. Such naming differences can complicate literature searches, database entries, and product verification.

Handling And Analytical Properties

AOD-9604 is typically supplied as a lyophilized white to off-white powder. In this form, it is relatively stable when kept cool, dry, and protected from light. Common storage recommendations place it at −20 °C or below for long-term retention. Reconstituted solutions are less stable and are often kept at 2–8 °C for short periods. Freeze-thaw cycles should be minimized because they can promote aggregation or loss of peptide content. Vials are usually sealed under inert gas to reduce oxidation.

Identity and purity are commonly checked with reversed-phase high-performance liquid chromatography and mass spectrometry. RP-HPLC separates the peptide from related impurities and can estimate purity by peak area. Mass spectrometry confirms molecular mass and helps detect sequence variants or truncations. Some laboratories use amino acid analysis or peptide mapping for additional characterization. No single method proves biological activity; these techniques establish chemical identity and purity only. They also require suitable reference standards for confident comparison.

Commercial AOD-9604 may vary in purity, counterion content, and residual moisture. Certificates of analysis often report HPLC purity, mass confirmation, and appearance, but testing methods differ between suppliers. Independent verification is sometimes used because labeled content may not match actual peptide amount. Stability under different pH and temperature conditions is not fully standardized across studies. Researchers generally treat lyophilized material as the reference form for weighing and reconstitution. Moisture content can affect accurate mass measurement.

Aod-9604 at a glance

PropertyValueNotes
Molecular classSynthetic peptideDerived from a fragment of human growth hormone
Sequence basishGH residues 176-191Commonly described as a 16-amino-acid fragment
AppearanceWhite to off-white powderTypical for lyophilized research peptides
SolubilitySoluble in water or aqueous bufferExact solubility depends on pH and purity
Common synonymsAOD9604; hGH 176-191Spelling and punctuation vary across sources

Identity And Research Background

AOD-9604 drew attention in the 1990s and 2000s as a potential anti-obesity agent. Early work explored both injectable and oral routes, which is unusual for a peptide of this size. Animal studies reported changes in fat metabolism without the growth-promoting or insulin-like effects associated with full-length growth hormone. Subsequent human trials produced mixed or modest results, and the compound did not obtain regulatory approval for weight management in major markets. It remains known mainly through research literature, sports anti-doping listings, and non-approved supplement advertising.

AOD-9604 is prohibited in sport by the World Anti-Doping Agency under the peptide hormone class. Its presence in a sample can be detected through mass spectrometry-based methods, although the exact assay depends on the laboratory. In research settings, material is often supplied as a lyophilized powder for reconstitution. Buyers and researchers should note that products labeled AOD-9604 may vary in purity and actual peptide content. Analytical certificates and independent testing are common ways to verify identity, but no global harmonized standard exists for all commercial lots.

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Mechanism and Regulatory Status

Proposed mechanisms for AOD-9604 focus on fat cells. Laboratory studies suggest the peptide can increase lipolysis, the breakdown of stored fat, and reduce lipogenesis, the formation of new fat. Unlike full human growth hormone, it does not appear to stimulate substantial IGF-1 production in the studies reported so far. Some evidence points to beta-adrenergic signaling, but the precise receptor targets and downstream pathways remain unresolved. The fragment is not thought to act through the classical growth hormone receptor.

Clinical development of AOD-9604 included trials in people with obesity. Reports from early-phase and mid-phase studies described modest or inconsistent changes in body weight. A phase IIb program did not meet its primary endpoint, and the compound was not approved for medical use. Differences in formulation, delivery route, and participant characteristics may explain some of the variation. Later investigations explored whether the peptide might have effects in other tissues, including cartilage.

Regulatory treatment of AOD-9604 is shaped by its classification as a peptide hormone. The World Anti-Doping Agency lists it as a prohibited substance, and many national anti-doping organizations adopt that list. It does not hold approval as a prescription medicine in the United States, the European Union, or other major markets. Products sold online are frequently labeled for research use only and may not undergo independent quality testing. Import and possession rules differ by country, so legal status depends on local law.

Identity and Research Context

Several names appear in scientific and commercial settings. AOD9604 and AOD-9604 are development codes used interchangeably, while hGH fragment 176-191 describes the same region. The peptide includes a disulfide bond between two cysteine residues, which helps shape its three-dimensional structure. Different suppliers may provide acetate or other salt forms, and purity can vary. These differences matter because analytical tests and biological assays can respond to the specific form being studied.

Early interest in AOD-9604 centered on whether a fragment of human growth hormone could influence fat metabolism without the broader effects of the full hormone. Cell and animal studies reported changes in fat storage and breakdown. Human trials followed, but the results were not strong enough to secure regulatory approval. The compound remains available for laboratory research, and its clinical potential is still described as uncertain. Studies continue to examine its activity and safety profile.

AOD-9604 is a synthetic peptide that corresponds to a short section of human growth hormone. It is commonly identified as hGH fragment 176-191 because its sequence matches residues at the C-terminal end of the hormone. The molecule contains sixteen amino acids and is made by solid-phase peptide synthesis. Researchers study it for metabolic effects rather than for the growth-promoting actions associated with full human growth hormone. Its small size distinguishes it from the complete 191-amino-acid hormone.

Regulation and Detection Context

Regulatory interest in AOD-9604 increased after high-profile anti-doping cases involving peptide products. In some cases, the substance was supplied under alternative names or in compounded preparations, complicating traceability. Sports tribunals and anti-doping panels have discussed whether the peptide was explicitly banned at the time of use, leading to clarifications by the World Anti-Doping Agency. For consumers and researchers, the legal status can vary by jurisdiction, and products marketed as research chemicals may lack independent quality verification.

AOD-9604 is listed as a prohibited substance in sport by the World Anti-Doping Agency. It falls under the peptide hormones, growth factors, related substances, and mimetics class on the prohibited list. Anti-doping organizations treat its presence in an athlete's sample as an adverse finding unless a therapeutic use exemption applies. The prohibition reflects concerns about performance enhancement in competitive settings and the difficulty of distinguishing exogenous peptide use from endogenous hormone fragments.

Detection of AOD-9604 in biological samples relies on analytical techniques capable of distinguishing a small synthetic peptide from related endogenous sequences. Liquid chromatography coupled with tandem mass spectrometry is commonly used for confirmatory analysis. Sample preparation may involve immunoaffinity enrichment or solid-phase extraction to concentrate the peptide. Because the molecule is small and may be present at low concentrations, assay sensitivity and specificity are ongoing analytical challenges. Laboratories also validate methods against reference materials when available.

Notes from published material

A schematic of the optical systems is shown in Figure 1. The variable UV-Vis absorbance detector's optical bench is showing how the flow cell is positioned after the optical system, including the monochromator, which typically has a physical slit and a moving grating, so it is illuminated by a selected wavelength, reaching a photo-diode. The bench of the diode array detector, however, is configured so that the flow cell is positioned before the optical parts, so that the beam containing the entire spectrum is passing through it. The optical parts consist also with a monochromator and a slit, but with a fixed grating, which disperses the light onto a diode array imaging element.

Hacker, Barton C.; Grimwood, James M. (1977). On the Shoulders of Titans - A History of Project Gemini (SP-4203) (PDF) (Report). NASA. Retrieved January 2, 2026. Spaceflight Mission Patches website NASA NSSDC spacecraft details NASA Gemini 4 press kit (65-158) (PDF) (Report). May 21, 1965. Archived from the original (PDF) on June 21, 2009. "GEMINI 4 - Ed White Spacewalk- Dual Camera, Real Speed, Restored Audio" on YouTube The short film Four Days of Gemini 4 is available for free viewing and download at the Internet Archive.

Ezrin, Calvin; Moloney, Peter J. (1959). "Resistance to Insulin Due to Neutralizing Antibodies". The Journal of Clinical Endocrinology & Metabolism. 19 (9): 1055–1068. doi:10.1210/jcem-19-9-1055. PMID 13821166. Moloney, P. J.; Aprile, M. A. (1959). "On the Antigenicity of Insulin: Flocculation of Insulin-Antiinsulin". Canadian Journal of Biochemistry and Physiology. 37 (6): 793–800. doi:10.1139/o59-086. PMID 13651981. Wardlaw, A. C.; Moloney, P. J. (1961). "The Assay of Insulin with Anti-Insulin and Mouse Diaphragm". Canadian Journal of Biochemistry and Physiology. 39 (4): 695–712. doi:10.1139/o61-071. PMID 13783129.

Sources: en.wikipedia.org

Background from the literature

== Early career == Starting in the 1970s Smith published peer-reviewed papers on several subjects, including mass spectrometry, ion cyclotron resonance mass spectrometry, ion-molecule reactions, molecular assemblies, and supercritical fluid solutions. This early work has led him to be considered an internationally recognized expert in mass spectrometry and separation techniques, and his research has led to advancements in instrumentation for the medical and environmental analysis fields, as well as biological research. In the medical field, Smith's work has produced benefits in the areas of drug testing, analysis of pharmaceuticals and medical diagnostics in the clinical arena. His most successful invention has been the combination of capillary electro-phoresis with mass spectrometry. By the end of the 1990s, Smith's achievements included the electrodynamic ion funnel and a micro-dialysis device for the rapid purification of samples analyzed using mass spectrometry. Other notable contributions have been in the fields of supercritical fluids and related reverse micelle phenomena. On August 22, 2000, Smith demonstrated and patented the electrodynamic ion funnel for highly efficient capture and focusing of ions in gases. He applied it for increasing the sensitivity of ESI-MS. His group has continued to refine and extend ion funnel technology, which is now widely applied in mass spectrometry and ion mobility instrumentation.

The effect of a mutation on protein sequence depends in part on where in the genome it occurs, especially whether it is in a coding or non-coding region. Mutations in the non-coding regulatory sequences of a gene, such as promoters, enhancers, and silencers, can alter levels of gene expression, but are less likely to alter the protein sequence. Mutations within introns and in regions with no known biological function (e.g. pseudogenes, retrotransposons) are generally neutral, having no effect on phenotype – though intron mutations could alter the protein product if they affect mRNA splicing. Mutations that occur in coding regions of the genome are more likely to alter the protein product, and can be categorized by their effect on amino acid sequence:

== S == Secondary ion mass spectrometry Supercritical fluid chromatography (SFC) Scanning transmission electron microscopy (STEM) Scanning tunneling microscope (STM) Scanning electron microscope (SEM)

== Honours and achievements == Essendon captain: 2010–2016 2× All-Australian team: 2012, 2013 3× Crichton Medal: 2009, 2010, 2012 AFLPA best captain award: 2012 Australia representative honours in international rules football: 2014 Yiooken Award: 2013

Sources: en.wikipedia.org

Frequently asked questions

Is AOD-9604 the same as human growth hormone?

No, it is a synthetic peptide fragment corresponding to a small portion of hGH. It is not the full 191-amino-acid hormone and does not reproduce all of hGH's effects.

What is the exact length of AOD-9604?

It is commonly described as a 16-amino-acid peptide based on residues 176-191 of human growth hormone. Some sources vary in notation, so checking the stated sequence is useful.

Does AOD-9604 occur naturally?

It is not typically described as a standalone natural hormone. The sequence is derived from the C-terminal region of human growth hormone, but the synthetic peptide is a laboratory-made construct.

How should AOD-9604 be stored?

Lyophilized powder is commonly stored at −20 °C or below, protected from light and moisture. Reconstituted solutions are typically kept refrigerated and used within a limited period.

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