What the label states, the lot delivers — net peptide mass, not gross powder weight, purity reported as measured rather than rounded up, and a Certificate of Analysis for every lot.
Net peptide mass, not powder weight; purity as measured, not rounded up; a COA per lot.
Net peptide + purity not rounded up. COA per lot.
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C-terminal fragment of human growth hormone (176–191)
Vialdyne primary owner
This Vialdyne page is the primary SEO owner for buyers evaluating HGH Fragment 176-191 through a pharmacy QA, clinic procurement, or regulated-sourcing workflow. It should answer whether the buyer can request a batch COA, release-test scope, destination-market review, and add-on documentation before moving into pricing or repeat inventory planning.
Overview
HGH Fragment 176-191 is the unmodified 16-residue C-terminal segment of human growth hormone, lifted directly from positions 176 through 191 of the 191-residue native HGH protein. The fragment preserves C-terminal-region lipolytic activity while leaving behind the central-region anabolic and IGF-1-stimulating effects that are characteristic of the full-length GH molecule. The critical distinction at the procurement-file level is between this SKU, which is the unmodified native sequence, and AOD9604, whose N-terminal residue is tyrosine (the tyrosine was introduced to support iodination tracking) where this native fragment carries phenylalanine; the two molecules are chemically distinct and produce different ESI-MS signatures, despite a confusingly similar catalogue naming convention across the broader peptide market. Vialdyne releases HGH Fragment 176-191 against a ≥99.0% main-peak HPLC specification, with the full identity stack documented on every released-batch COA. The relevant values: CAS number 66004-57-7, molecular formula C78H123N23O22S2, average MW 1799.1 g/mol, and primary sequence FLRIVQCRSVEGSCGF. The sequence carries two cysteine residues at internal positions 7 and 14, which under oxidative storage conditions can pair into an intramolecular disulfide bridge. This disulfide-bridging behaviour is the most common identity-confirmation concern at receiving inspection: the reduced and oxidised forms differ by 2 Da in ESI-MS and elute at different RP-HPLC retention times. The released-batch COA documents which form the lot represents. Six nominal strengths from 1 to 15 mg cover bench-scale and dispensing-scale workflows.
Applications & buyer fit
GH-axis peptides ship to two main buyer types: compounding pharmacies dispensing under physician supervision, and research labs studying somatotropic-axis pharmacology. Pharmacies typically want sterile-filled vials with the full release packet (sterility, endotoxin, CCI); labs typically want loose-format lyophilized powder with sequence verification. Blends (the CJC-1295 / Ipamorelin combination is the canonical example) are usually co-lyophilized rather than solution-mixed for potency stability.
Sourced for
Buyer fit
Documentation that ships
Procurement note: Sterile-filled vials are available with the full release packet (sterility, endotoxin, CCI); loose lyophilized powder ships with sequence verification.
Primary buyer fit: academic and contract research laboratories and 503A / 503B compounding pharmacies.
Specifications
Certificate of Analysis
Published released-batch COAs for HGH Fragment 176-191, every lot HPLC-verified. These are previews — request the full high-resolution certificate for any lot.
VerifiedRequest full COA →HGH Fragment 176-191
VD260428-FRAG107 · 99.68%
VerifiedRequest full COA →HGH Fragment 176-191
VD260428-FRAG108 · 99.39%
VerifiedRequest full COA →HGH Fragment 176-191
VD260428-FRAG109 · 99.42%
VerifiedRequest full COA →HGH Fragment 176-191
VD260428-FRAG104 · 99.66%
VerifiedRequest full COA →HGH Fragment 176-191
VD260428-FRAG105 · 99.53%
VerifiedRequest full COA →HGH Fragment 176-191
VD260428-FRAG106 · 99.11%
Regulatory note
Because the unmodified fragment and the AOD9604-modified analog (bearing an N-terminal tyrosine) are not chemically equivalent, they are readily mixed up. Before you place an order, verify the precise fragment identity — unmodified versus AOD9604-modified — against the batch COA.
Selected literature
Frequently asked questions
Mass spec at receiving inspection is the diagnostic test. The two molecules differ at the N-terminal residue, AOD9604 carries an N-terminal tyrosine where this native fragment carries phenylalanine, producing a 16-residue molecule with theoretical MW around 1815 Da, while HGH Fragment 176-191 is the unmodified 16-residue sequence at 1799.1 Da theoretical. The ~16 Da delta (tyrosine adds one oxygen relative to phenylalanine) is unambiguous on an ESI-MS scan and is the test we recommend for first-time supplier qualification when sourcing either form. Secondary confirmation comes from RP-HPLC retention time, the tyrosine hydroxyl shifts AOD9604 elution relative to the native fragment under typical gradient conditions. Either way, never rely on label alone; the released-batch mass must match the ordered form.
The fragment sequence FLRIVQCRSVEGSCGF contains two cysteines at internal positions 7 and 14. Under reducing conditions during synthesis the cysteines remain as free thiols; under oxidative conditions during downstream storage and reconstitution they can pair into an intramolecular disulfide bridge. The reduced and oxidised species differ by 2 Da in ESI-MS and elute at distinct RP-HPLC retention times, making the form readily distinguishable at QC. Most published research uses the oxidised (disulfide-bridged) form, which is the more stable solid-state species. The released-batch COA documents which form the lot represents, which matters operationally for any protocol that specifies one form or the other.
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