What's on the label is the measured result — net peptide mass, not gross powder weight, plus RP-HPLC purity, on a lot-numbered COA for every batch.
Net peptide mass and RP-HPLC purity — a lot-numbered COA for every batch.
Net peptide mass + HPLC purity, per lot.
PCAC will review 7 peptides for the 503A bulks list, BPC-157, KPV, TB-500, MOTS-c, Emideltide, Semax, Epitalon. Read our briefing →
PCAC will review 7 peptides for the 503A bulks list. Read →
FDA PCAC reviews 7 peptides in July. Read →
Long-Arg3 IGF-1 (long-acting IGF-1 analog)
PeptideXpo buyer fit
This PeptideXpo page is intentionally positioned for distributors, OEM buyers, and procurement teams comparing IGF-1 LR3 inside a wider peptide catalog. It is not trying to be the deepest single-molecule monograph; the differentiated intent is assortment planning, export-ready documentation, fill-size comparison, and whether this SKU belongs in a broader buyer program.
Overview
IGF-1 LR3 (Long R3 IGF-1) is an engineered 83-amino-acid analog of native IGF-1 with two structural modifications: a 13-amino-acid N-terminal extension and an Arg substitution at position 3 (in place of native Glu3). The N-terminal extension came originally from a serendipitous E. coli fusion-protein construct and was found to dramatically reduce binding affinity for the IGF-binding-protein family (IGFBPs), while the Arg3 substitution further suppresses IGFBP interaction. Both modifications together produce a circulating analog that is largely free of IGFBP sequestration, the practical consequence is roughly 3-fold higher biological potency in cell-proliferation assays compared with native IGF-1 at equivalent molar concentrations, plus an extended functional half-life because the molecule is not removed from circulation by IGFBP-mediated clearance. PeptideXpo supplies recombinant IGF-1 LR3 as a lyophilized powder at ≥99.0% HPLC purity. As a recombinant protein expressed in E. coli, the release packet emphasizes both chemical purity (RP-HPLC) and biological activity verification, the latter typically by SDS-PAGE for size, plus optional cell-proliferation bioassay (3T3 or MCF-7 cells) for activity confirmation. Endotoxin (LAL) is included by default for IGF-1 LR3 because the recombinant-protein process can carry over higher endotoxin loads than synthetic peptides. Three standard fill sizes (100 mcg, 1 mg, 2 mg) cover cell-culture aliquot scales through in vivo research workflows.
Who buys this, and why
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 bulk 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.
Primary buyer fit: academic and contract research laboratories.
Specifications
Documentation available on request
Regulatory note
Sold as a bulk active for research and for compounding-pharmacy formulation where local regulations permit (notably 503A / 503B in the United States and analogous regimes elsewhere). Not a finished dosage form. Sterile-filled vials are available with full release documentation; the buyer is responsible for verifying scheduling and dispense requirements in the destination market.
Frequently asked questions
Native IGF-1 is heavily sequestered by IGFBPs in serum and cell-culture environments, typically less than 1% of total IGF-1 is free at any given time. This makes dose-response work and concentration-controlled experiments difficult because the effective free concentration is hard to predict. IGF-1 LR3's two engineered modifications (N-terminal extension and Arg3 substitution) dramatically reduce IGFBP binding, producing a more linear and predictable dose-response. The practical readout in cell-proliferation assays is roughly 3-fold higher potency than native IGF-1 at equivalent molar concentrations, with substantially less inter-experiment variability.
At 83 amino acids, IGF-1 LR3 is at the boundary between large peptide and small protein, practically, it's produced by recombinant expression in E. coli rather than solid-phase synthesis. The analytical packet therefore differs from typical synthetic peptides: RP-HPLC for chemical purity, SDS-PAGE for size confirmation, mass spec (sometimes intact-mass or peptide-mapping), plus a bioactivity readout (cell-proliferation assay) is recommended because recombinant material's biological activity can vary with folding even when chemical purity is high. Endotoxin (LAL) is essential for IGF-1 LR3 because the E. coli expression system requires careful endotoxin clearance during purification.
Lyophilized IGF-1 LR3 reconstitutes in 0.6% acetic acid (rather than plain water), the slight acidification keeps the protein in monomer form and avoids aggregation that can occur at neutral pH on dilute reconstitution. After reconstitution, dilute working stocks should be prepared in cell-culture-grade BSA-containing buffer (typically 0.1% BSA) to prevent adsorption to glass and plastic surfaces at low working concentrations, this is critical for cell-culture work at sub-100 ng/mL. Working stocks should be aliquoted into single-use volumes and held at -20 °C; lyophilized product follows the standard 24-month re-test window.
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