IGF-1 LR3 1mg

The difference matters more than the residue count suggests. Native IGF-1 in circulation is almost entirely sequestered — largely in a ternary complex with IGFBP-3 and the acid-labile subunit — and bound IGF-1 cannot engage its receptor. LR3's two modifications reduce that affinity, which is a binding property: in a medium containing binding proteins, less of what is added disappears into complexes, so the unbound fraction at a given total concentration is higher.

That is the entire purpose of the molecule, and in the setting it was designed for — a dish, where secreted binding proteins are an experimental nuisance — it is a sensible design. Outside one it is not a design at all: the binding-protein system is a control mechanism on a growth factor with receptors on nearly every tissue, not an inefficiency an engineer improved upon, and the reasoning does not transfer.

LR3 has no clinical development programme and no characterisation in human circulation, and nothing here describes what it would do there. What enhanced potency has been reported for the Long analogues comes from binding-protein resistance rather than from stronger receptor engagement — that is the distinction Francis and colleagues drew in 1992.

The regulatory difference is sharper still: no approved IGF-1 product's marketing authorisation extends to this 83-residue analogue; it holds none of its own, anywhere.

Add native IGF-1 to a culture and an unpredictable fraction is immediately captured by binding proteins the cells themselves have secreted into the medium. How much depends on cell type, density, medium composition and how long the culture has been running, so the nominal concentration and the effective concentration diverge — and diverge differently each time.

That matters because comparing conditions requires that the variable under study is the one that differs: if effective IGF-1 concentration tracks cell density, a density experiment and a concentration experiment are confounded with one another. An analogue that resists those binding proteins keeps the two figures tracking together.

That is a reproducibility gain rather than a potency gain, and it is the application LR3 was developed for. The corollary is worth stating plainly: searches under "IGF-1 LR3" and "Long R3 IGF-1" return essentially no primary research literature. The compound is real and its design rationale is sound, but it exists as a reagent rather than as a research subject, and anyone expecting to find trials of it will not.

The 1mg vial suits typical in-vitro protocols; larger fills are unusual because working concentrations are low. Reported applications include:

At 83 residues with three disulfide bonds and a folded tertiary structure, IGF-1 LR3 sits well past the 40-amino-acid line that regulatory frameworks treat as the boundary between peptide and protein. It is produced by recombinant expression rather than solid-phase synthesis, and that changes what can go wrong with it.

A synthetic peptide accumulates deletion sequences from incomplete couplings, which differ from the target by one residue's mass and are visible to mass spectrometry. A recombinant protein does not accumulate those — ribosomal synthesis does not fail one residue at a time — though the route has product-related species of its own, including truncated and clipped chains and N-terminal methionine heterogeneity.

On top of that it carries host cell protein, host DNA and, from bacterial expression, endotoxin, none of which appears in a protein purity figure at all. Six cysteines can pair fifteen ways and only one pairing is correct, and a misfolded isomer has identical mass to the correct protein.

Reading this material's paperwork with synthetic-peptide expectations means checking for failures this production route does not have while missing the ones it does.

Three distinctions, stated plainly because each is a common and consequential confusion. It is not a licensed medicine: an approved recombinant IGF-1 product exists, but it is the native 70-residue hormone and its authorisation extends to this 83-residue analogue in no respect — see our note on regulatory status.

It is not the body's own IGF-1: that is the endogenous 70-residue hormone, and we publish nothing about clinical measurement or its interpretation. And it is not exempt from anti-doping rules: IGF-1 and its analogues sit in WADA class S2 — peptide hormones, growth factors, related substances and mimetics — prohibited at all times, in and out of competition, and IGF-1 sits in WADA class S2, which covers growth factors and their mimetics as a category rather than by naming each analogue, so a structural modification creates no exemption. Supplied for in-vitro laboratory research only.

Store the lyophilised vial at -20°C, sealed and protected from light. Bacteriostatic water (0.9% benzyl alcohol) is the house solvent across this catalogue, but the benzyl alcohol is a preservative for repeatedly punctured vials rather than a stabiliser, and it does nothing for a folded protein at neutral pH. Reconstituted in bacteriostatic water, refrigerate at 2–8°C and use within 14 days; an acidified diluent carries no preservative and no antimicrobial margin, so aliquot into single-use volumes and freeze at -20°C rather than drawing repeatedly from one vial.

Two handling points apply here that do not apply to a short peptide. A folded protein held by three disulfide bonds can lose activity through denaturation or disulfide scrambling while remaining chemically intact and identical by mass, so a failed vial does not necessarily look failed on an analysis — proteins unfold at air-liquid interfaces, which is why shaking and foaming matter and freeze-thaw cycling is particularly damaging.

And adsorption to glass and plastic is significant at the microgram working quantities this compound is used in, which is what low-binding consumables and carrier protein in the buffer exist to mitigate.

Every IGF-1 LR3 1mg vial is independently HPLC-UV tested to ≥98% purity by an accredited independent laboratory, with mass-spectrometry identity confirmation against the 9,112 Da molecular weight printed on the batch certificate. The signed PDF Certificate of Analysis is supplied with every order and matches the vial lot number.

One honest qualification belongs here: purity and mass establish composition, not conformation. A misfolded disulfide isomer has the same mass as the correctly folded protein, so no HPLC figure and no mass spectrum distinguishes them, and host cell protein, host DNA and endotoxin do not appear in a chromatographic purity figure either.

That is a limitation of the standard analysis rather than of any particular batch, and it applies to every supplier of a disulfide-containing recombinant protein.

UK Peptides holds IGF-1 LR3 1mg in temperature-controlled storage, dispatches same-day in insulated cold-chain mailers on Royal Mail Tracked 24, and provides third-party HPLC verification on every batch. The lyophilised powder is the stable form; the handling that matters begins once it is in solution, where a folded protein can lose activity through denaturation or disulfide scrambling while remaining chemically intact and identical by mass.

It is supplied strictly for in-vitro laboratory research: it is not a licensed medicine, it is not approved by the MHRA for human or veterinary use, and IGF-1 and its analogues are prohibited in sport at all times under WADA class S2.