What IGF-1 LR3 is
IGF-1 LR3, also written Long R3 IGF-I, is an 83-residue analog of human insulin-like growth factor 1. It differs from the 70-residue native chain in two places: a 13-residue N-terminal extension, Met-Phe-Pro-Ala-Met-Pro-Leu-Ser-Ser-Leu-Phe-Val-Asn, and arginine in place of glutamic acid at position 3 of the native numbering. “Long” names the extension and “R3” names the substitution. Six cysteines form three internal disulfide bonds in the correctly folded molecule.
At a little over 9.1 kDa, this is a small protein rather than a peptide in the sense used for most of our catalog, and chains of this length are normally produced by recombinant expression rather than stepwise synthesis. It should not be confused with native IGF-1 (about 7649 Da) or with the 70-residue R3-only variant, both of which lack the extension and weigh correspondingly less.
IGF-1 LR3 1mg specification
| Catalog name | IGF-1 LR3 |
|---|---|
| Sequence | MFPAMPLSSLFVNGPRTLCGAELVDALQFVCGDRGFYFNKPTGYGSSSRRAPQTGIVDECCFRSCDLRRLEMYCAPLKPAKSA (three disulfides) |
| Molecular formula | C400H619N111O115S9 (three disulfides formed) |
| Average molecular mass | approx. 9111 g/mol, disulfide-bonded form |
| CAS number | 143045-27-6 |
| Amount per vial | 1 mg |
| Form | Lyophilized powder, sealed vial |
| HPLC purity | ≥98% |
| Shelf life | 36 months in the sealed vial |
How IGF-1 LR3 is analyzed
Protein-sized analytes call for wide-pore packings, typically 300 angstrom C4 or C8, and IGF-1 LR3 elutes late as a single main peak when homogeneous. Tyrosines and phenylalanines but no tryptophan give moderate 280 nm absorbance, with purity read near 214 nm. Intact mass is the key identity check: the oxidized form sits near 9111.5 Da, the fully reduced chain about 6 Da heavier, and each oxidized methionine (three in total, two of them in the extension) adds 16 Da. Electrospray gives a charge ladder, with the 8+ ion near m/z 1140 and the 10+ near m/z 912.
Mass cannot confirm correct disulfide pairing, because all fifteen possible arrangements of six cysteines weigh the same; mispaired isoforms may appear as shoulders only if the method resolves them. The independent reverse-phase HPLC result for IGF-1 LR3 1mg is published on this page, and with no batch or lot identifier printed on the vial, its crimp and cap color is what links it to that result.
Research contexts for IGF-1 LR3
- IGF-1 receptor binding assays in cell-free or cultured-cell systems
- IGF-binding protein interaction studies comparing the analog with native IGF-1 in vitro
- Disulfide mapping and folding-isoform analysis by peptide mapping and non-reduced electrophoresis
- Intact-mass and charge-state distribution studies of small proteins by LC-MS
IGF-1 LR3 1mg is a reference protein for in-vitro laboratory research and is not for use in people or animals.
IGF-1 LR3 questions
Is 7649 Da ever the right mass for IGF-1 LR3?
No. That figure belongs to native 70-residue IGF-1. The LR3 analog carries 13 extra residues and should read a little over 9.1 kDa.
Why might two documents quote 9111 and 9118 Da?
The lower figure describes the molecule with its three disulfides formed; the higher one describes the reduced chain with six free thiols. A document should state which form it means.
Why does IGF-1 LR3 call for a C4 column rather than C18?
Short-chain, wide-pore phases let a protein-sized molecule reach the bonded surface and elute completely, giving sharper peaks than narrow-pore C18.
Buying IGF-1 LR3 1mg in the USA
IGF-1 LR3 1mg goes out from a US site with tracking attached, and shipping is waived on orders exceeding $100. Laboratories that need matched material across a series of binding or folding studies can request bulk pricing. Orders are fulfilled only for research institutions, licensed researchers, universities and laboratory R&D purchasers. For the sequence alignment against native IGF-1, read What Is IGF-1 LR3? Sequence, Identity and Analytical Profile.
IGF-1 LR3 1mg is supplied for in-vitro research alone; it is not for human or veterinary use, and no preparation or dosing guidance is given.
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