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HGH Fragment 176-191 | CAS: 66004-57-7

CAS Number:
66004-57-7
Chemical Classification:
Research peptide

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The HGH Fragment 176-191 region (CAS 66004-57-7) represents the lipolytic C-terminal portion of human growth hormone and is applied when investigators wish to separate metabolic fragment activity from full-length GH receptor signaling. Because the truncated sequence does not replicate complete GH biology, experimental framing must account for receptor-context limitations that differ from intact hormone studies. Groups variously examine adipocyte lipolysis markers, substrate-oxidation shifts in lean tissue, or comparative responses against GH(1-191) in cell models. Practical deployments include differentiated adipocyte incubations with glycerol-release endpoints, rodent metabolic-chamber sessions with clamped nutrition, and dose-titration in primary hepatocyte cultures. Research-grade supply includes COA, LC-MS, HPLC, and NMR verification.

CAS
66004-57-7
Molecular Formula
C78H125N23O23S
Molecular Weight
1817.1 g/mol
Purity
≥98%
Appearance
White lyophilized powder
Storage
Store at -20°C

Analytical Documentation

COA✓ Available
LC-MS✓ Available
HPLC✓ Available
NMR✓ Available

Research Inquiry

Overview

HGH Fragment 176-191 is a synthetic peptide corresponding to the C-terminal region of human growth hormone spanning amino acids 176 through 191, sometimes referred to as AOD9604 in related research contexts. Unlike full-length GH, this truncated fragment does not bind the GH receptor and therefore does not replicate classical JAK-STAT growth signaling. Instead, research focuses on purported lipolytic and metabolic activities mediated through distinct mechanisms that remain under investigation in preclinical models. The fragment serves as a tool for separating GH receptor-dependent anabolic effects from C-terminal sequence-associated metabolic phenotypes in rodent adipose and liver research. Its small size facilitates tissue penetration studies and structure-activity comparisons with adjacent GH sequence truncations in endocrine-metabolic laboratories. Supplied at ≥98% purity (C78H125N23O23S; 1817.1 g/mol), this material supports controlled laboratory investigation under research-use-only conditions.

Mechanism of Action

HGH Fragment 176-191 does not activate GH receptor or prolactin receptor in standard binding assays, distinguishing its mechanism from intact growth hormone. Research models propose indirect modulation of lipolysis through beta-adrenergic sensitization, adipocyte lipid mobilization, and altered expression of lipogenic enzymes without elevating IGF-1 or affecting glucose tolerance at equivalent research doses in some rodent studies. Mechanistic pathways remain debated, with evidence for involvement of adipose-specific receptors or membrane-associated binding sites rather than canonical GH signaling. The fragment allows investigators to test whether C-terminal GH sequences independently influence substrate oxidation in high-fat-fed animal research. Comparative experiments with GH receptor agonists and antagonists clarify pathway independence.

Receptor Binding & Signaling

No high-affinity binding to GH receptor (GHR) is detected in standard radioligand displacement studies at research concentrations. Off-target screening excludes meaningful activation of prolactin receptor, GHS-R1a, or common metabolic GPCRs. Putative low-affinity binding sites on adipocyte membranes have been proposed in exploratory research but lack consensus orthosteric identity. Mechanistic studies rely on phenotypic endpoints rather than defined single-receptor occupancy.

Research Applications

Adipocyte lipolysis research

Primary adipocyte cultures and rodent models use HGH Fragment 176-191 to measure glycerol release, hormone-sensitive lipase phosphorylation, and perilipin remodeling without confounding GH receptor-mediated IGF-1 elevation. Pairing with beta-adrenergic blockade tests proposed sensitization mechanisms. Research focuses on lipid mobilization biochemistry in controlled metabolic studies.

GH pathway disaggregation experiments

Co-administration with GH receptor blockers or full-length GH compares body composition and serum IGF-1 endpoints in rodent research. HGH Fragment 176-191 isolates C-terminal sequence effects from intact GH anabolic signaling. These factorial designs advance understanding of growth hormone domain function in basic science.

Metabolic phenotyping in diet models

High-fat diet rodent studies examine whether fragment administration modifies fat mass, locomotor activity, or indirect calorimetry metrics independent of hyperglycemia changes in research protocols. Longitudinal designs document adipose depot-specific responses. Results inform structure-function maps of GH without therapeutic claims.

Peptide stability and proteolysis studies

The 16-amino-acid fragment serves as a model substrate for evaluating peptidase resistance and serum stability compared with larger GH domains in biochemical research. Mass spectrometry tracks degradation products in plasma incubations. Such work supports analytical method development for small peptide quantification.

Molecular Information

Sequence & Chain Summary

Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe (GH residues 176-191).

Modification Type

Disulfide bond between Cys residues (positions 182 and 189 in full GH numbering).

Structural Notes

The peptide contains an intramolecular disulfide loop influencing conformation and HPLC retention. Correct oxidative folding is verified during synthesis QC. Small molecular weight enables MALDI-TOF confirmation. Reduced forms may appear as impurities detectable by RP-HPLC. Batch-specific molecular characterization—including mass confirmation and purity profiling—is available through COA, LC-MS, HPLC, and NMR documentation supplied with HGH Fragment 176-191.

Molecular Formula
C78H125N23O23S
Molecular Weight
1817.1 g/mol
Purity Specification
≥98%

Experimental Notes

Stability

Lyophilized material stable at −20°C. Disulfide integrity sensitive to reducing agents and extreme pH. Reconstituted solutions degrade at room temperature over hours; refrigerate or freeze aliquots. Avoid DTT or TCEP in storage buffers unless studying reduced state. Lyophilized HGH Fragment 176-191 should be protected from repeated freeze-thaw cycles, moisture, and prolonged exposure to ambient light where applicable. Analytical integrity is best preserved when material is stored under the conditions specified on the certificate of analysis.

Storage Conditions

Store at -20°C. HGH Fragment 176-191 is supplied as white lyophilized powder. For long-term archival storage in research inventories, maintain sealed containers with desiccant where recommended and document lot numbers for traceability across experimental runs.

Laboratory Handling

Reconstitute gently in sterile water or PBS. Do not assume GH receptor activity in assay design. Document disulfide status if comparing batches. Use low-bind consumables for dilute solutions. Reconstitute only with appropriate research-grade solvents compatible with your assay format. Allow vials to reach equilibrium before opening, work under clean bench conditions, and label all working solutions with concentration, date, and researcher ID per institutional SOPs.

Related Peptides

Growth Hormone Peptides →Peptide CAS database →

Frequently Asked Questions

Research-focused answers about HGH Fragment 176-191. For laboratory use only — not medical advice.

What is HGH Fragment 176-191 used for in research?
HGH Fragment 176-191 is supplied for metabolic and adipose biology research exploring C-terminal growth hormone peptide activity independent of GH receptor signaling. Not for human or veterinary administration.
How does HGH Fragment 176-191 work biologically?
This GH-derived fragment does not activate GH receptor but is studied for effects on adipocyte lipid metabolism and related pathways in preclinical models through mechanisms distinct from intact growth hormone.
What receptors does HGH Fragment 176-191 interact with?
Standard research assays show no significant GH receptor binding. Proposed adipose-associated binding sites remain under investigation without a universally accepted primary receptor target.
Is HGH Fragment 176-191 stable at room temperature?
Lyophilized material stable at −20°C. Disulfide integrity sensitive to reducing agents and extreme pH. Reconstituted solutions degrade at room temperature over hours; refrigerate or freeze aliquots. Avoid DTT or TCEP in storage buffers unless studying reduced state. For short-term laboratory workflows, minimize time at room temperature and return unused material to recommended storage promptly. HGH Fragment 176-191 is not formulated for ambient long-term storage.
What is the recommended storage condition for HGH Fragment 176-191?
Store at -20°C. Store lyophilized material in a dedicated −20°C freezer, protect from moisture ingress, and avoid repeated temperature cycling. Reconstituted solutions should be aliquoted and frozen if not used within the validated window of your internal stability study.