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a vial of H-Fragment 176-191 5mg
an info card for HGH 176-191

H-Fragment 176-191

$41.00

  • Contents: H-Fragment 176-191 (hGH C-terminal fragment; native sequence residues 176-191)
  • Form: Lyophilized powder
  • Purity: >99%
Quantity Discount Price
1 - 3 - $41.00
4 - 7 10% $36.90
8 + 18% $33.62
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Description

H-Fragment 176-191 is a synthetic 16-amino acid peptide corresponding to the native C-terminal sequence of human growth hormone, residues 176 through 191. It contains the disulfide bridge between the cysteine residues in the sequence and retains the phenylalanine residue at the N-terminus as it appears in the intact GH molecule. Unlike full-length human growth hormone, H-Fragment 176-191 does not bind the GH receptor and does not produce IGF-1-mediated effects in cell-based systems. Its research interest lies specifically in the beta-3 adrenergic receptor signaling pathway in adipocyte models.

Chemical Information

  • Chemical Name: H-Fragment 176-191 (hGH Fragment 176-191; native GH C-terminal sequence)
  • Also Known As: hGH Fragment 176-191; GH 176-191; lipolytic fragment of hGH
  • Compound Class: Synthetic GH C-terminal peptide fragment (native sequence)
  • Sequence: Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Glu-Gly-Ser-Cys-Gly-Phe (positions 176-191 of hGH)
  • Molecular Formula: C78H125N23O23S2
  • Molecular Weight: 1,817.12 g/mol
  • Disulfide Bridge: Cys7-Cys14 (intramolecular; present in native sequence)
  • N-terminal residue: Phenylalanine (native GH sequence; distinguishes it from AOD-9604, which substitutes tyrosine)
  • Production: Solid-phase peptide synthesis (SPPS)

Applications

  • Beta-3 adrenergic receptor (ADRB3) signaling research in adipocyte models. H-Fragment 176-191 activates beta-3-AR pathways in white and brown adipose tissue cell models; the Heffernan 2001 PMID 11713213 study confirmed this receptor dependency using knockout models, making it the primary mechanistic reference for both this compound and AOD-9604
  • GH receptor-independent lipid metabolism pathway research. Unlike full-length GH, H-Fragment 176-191 does not bind the GH receptor and does not stimulate IGF-1 production; it is used in models studying lipid metabolism signaling that is mechanistically downstream of beta-3-AR activation rather than GH receptor engagement
  • Structural comparison studies with AOD-9604. H-Fragment 176-191 (native Phe at N-terminus) and AOD-9604 (Tyr substitution at N-terminus, enabling radioiodination) are structurally distinct compounds derived from the same GH C-terminal region; researchers studying how the single N-terminal amino acid substitution affects receptor interaction, enzymatic stability, and pharmacokinetic behavior use both compounds in parallel
  • Radioiodination-independent research designs. AOD-9604’s tyrosine substitution was introduced specifically to enable radioiodination (125I labeling) for receptor binding assays and pharmacokinetic tracing. H-Fragment 176-191 with native Phe provides the unmodified reference sequence for studies where radioiodination is not required
  • Intracellular cAMP and PKA pathway research in adipocytes. ADRB3 activation elevates intracellular cAMP, which activates PKA and initiates downstream lipolytic signaling cascades. H-Fragment 176-191 is studied as the ADRB3 activating agent in models examining this signaling cascade in adipocyte cell populations
  • Antilipogenic versus lipolytic signaling. Research documents both lipolysis stimulation and lipogenesis inhibition as effects of the GH 176-191 region. H-Fragment 176-191 is used in models examining which of these lipid metabolism effects predominate under different experimental conditions

Storage and Handling

Store lyophilized powder at -20C for long-term stability, or at 2-8C for short-term use. Protect from heat, moisture, and direct light. The disulfide bridge in the native sequence is susceptible to reducing conditions; avoid reducing agents in reconstitution buffers. Reconstitute immediately before use and avoid repeated freeze-thaw cycles to preserve compound integrity.

Compliance Notice

H-Fragment 176-191 is for laboratory research use only. It is not for human or veterinary use and carries no therapeutic, diagnostic, or clinical indication. This product has not been evaluated by the FDA. By purchasing this product, the buyer confirms that they will follow appropriate institutional safety procedures and use it exclusively for controlled research.

Frequently Asked Questions

What is H-Fragment 176-191 and how does it differ from AOD-9604?

H-Fragment 176-191 is a synthetic 16-amino acid peptide corresponding to the native C-terminal sequence of human growth hormone (residues 176-191), with phenylalanine at the N-terminus as it appears in intact GH. AOD-9604 is a structurally modified version of the same C-terminal region in which the N-terminal phenylalanine is substituted with tyrosine. This single amino acid change was introduced to enable radioiodination with 125I for receptor binding assays and pharmacokinetic tracing studies. Both compounds share the same disulfide bridge and core beta-3 adrenergic receptor research mechanism; the structural difference is relevant primarily for research designs requiring radiolabeling or for studies examining how N-terminal residue identity affects receptor interaction and enzymatic stability.

Why does H-Fragment 176-191 not affect GH receptor signaling or IGF-1 production?

Full-length human growth hormone binds the GH receptor through its site 1 and site 2 binding domains, which are located in the N-terminal and central regions of the molecule. The C-terminal fragment (residues 176-191) does not contain these binding domains and therefore does not engage the GH receptor. Without GH receptor activation, the downstream JAK2/STAT5 signaling cascade that drives IGF-1 gene expression in hepatocytes is not activated. This receptor exclusivity is what makes H-Fragment 176-191 a useful research tool for studying GH-related lipid metabolism biology without the confounding effects of GH receptor signaling on growth, glucose metabolism, and IGF-1 production.

What is the significance of the beta-3 adrenergic receptor pathway in H-Fragment 176-191 research?

The beta-3 adrenergic receptor (ADRB3) is expressed primarily in white and brown adipose tissue and mediates intracellular cAMP elevation upon activation, driving PKA-dependent lipolytic signaling cascades. The Heffernan et al. 2001 study demonstrated that the lipid metabolism effects of the GH 176-191 fragment were abolished in beta-3-AR knockout mice while remaining intact in wild-type controls -- establishing ADRB3 as the primary receptor through which this GH C-terminal region exerts its adipose tissue biology effects. This receptor dependency is the mechanistic anchor for H-Fragment 176-191 research and the framework within which experimental designs using this compound are interpreted.

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