IGF1-DES

Overview

IGF1-DES — properly DES(1-3)IGF-1 — is a truncated form of insulin-like growth factor 1 lacking the first three residues of the sequence. It is studied for the same reasons as IGF1-LR3: it evades the binding proteins that regulate IGF-1, and is correspondingly more active in tissue.

It is not part of our catalogue. It is documented because it and LR3 are the two standard approaches to the same problem, and each is easier to understand alongside the other.

Chemical identity

• Also known as: DES(1-3)IGF-1, des-IGF-1
• Length: 67 residues — IGF-1’s 70 minus the N-terminal Gly-Pro-Glu
• Molecular weight: approximately 7,370 g/mol
• Classification: Truncated IGF-1 variant

A note on this data. Unlike every other compound documented in this library, DES(1-3)IGF-1 does not appear in the PubChem chemical database under any of the names it is known by, so its formula and CAS number could not be independently confirmed. The molecular weight above is derived rather than looked up: human IGF-1 is approximately 7,649 g/mol, and removing the Gly-Pro-Glu tripeptide accounts for roughly 283, giving about 7,366.

That derivation is sound arithmetic but it is not a substitute for a registry entry, so the figure is given as approximate. No molecular formula or CAS number is stated here because neither could be verified, and publishing an unverified identifier on a page arguing for analytical rigour would be self-defeating. Anyone requiring exact figures should obtain them from a supplier’s certificate and check them independently.

Three residues, and why they matter so much

The modification is the smallest possible: delete glycine, proline and glutamate from the N-terminus and leave the remaining 67 residues untouched. No substitutions, no additions.

The effect is out of proportion to the change, and the reason is that those three residues are part of what IGF-binding proteins grip. Over 95% of circulating IGF-1 is held bound and inactive by IGFBPs, principally IGFBP-3; only the small free fraction reaches receptors. Removing the N-terminal tripeptide substantially reduces that binding, so far more of the molecule is free to act.

Reported potency in tissue is severalfold that of intact IGF-1 — not because it binds the receptor better, but because so much less of it is sequestered. That distinction is the same one made on the LR3 page, and it applies with equal force here: this is a compound that escapes regulation rather than one that signals more strongly.

Truncation versus extension

The two IGF-1 analogues documented here reach the same destination by opposite routes, which makes them a useful pair:

• IGF1-DES — removes three residues from the N-terminus. 67 residues, around 7,370 g/mol.
• IGF1-LR3 — adds a 13-residue extension and substitutes arginine at position 3. 83 residues, around 9,118 g/mol.

Both reduce IGFBP affinity. One does it by deleting the binding determinant, the other by masking it and adding bulk. The result is a difference of sixteen residues and roughly 1,750 g/mol between two molecules designed for the same purpose — and a clear illustration that in protein engineering, subtraction and addition can be equally valid answers to the same question.

The practical difference between them is duration: LR3’s extension gives it a longer reported half-life, while DES clears faster. Which is preferable depends on whether sustained exposure or a shorter pulse suits the experiment.

It occurs naturally

This is the more interesting distinction between the two, and it is easy to miss.

LR3 is entirely artificial — the 13-residue extension comes from an unrelated protein and exists nowhere in nature. DES(1-3)IGF-1 is different: it has been isolated from biological material, including bovine colostrum and fetal brain tissue, where it appears to arise from proteolytic processing of intact IGF-1.

That has a genuine implication. A naturally occurring truncation suggests the cleavage may be a physiological regulatory step rather than an accident — a way of locally increasing IGF-1 activity by releasing it from binding-protein control in a particular tissue. Whether that is its function is not established, but it means DES(1-3)IGF-1 can be studied as an endogenous variant rather than only as an engineered tool, which LR3 cannot.

Production and handling

Like LR3, this is a recombinant protein rather than a synthetic peptide — 67 residues with disulphide bonds is well beyond practical solid-phase synthesis. Everything on the IGF1-LR3 page about recombinant production applies here: folding rather than sequence is the critical variable, host cell proteins and endotoxin are the relevant impurities, and a bioactivity assay rather than a mass figure is what establishes the material is active.

Handling follows the same rules. Never shake; foaming unfolds proteins. Avoid reducing agents, which open the disulphides that hold the fold. Aliquot rather than repeatedly freeze-thawing.

Purity and analytical verification

The recombinant considerations from the LR3 page apply unchanged, and one point is specific to this molecule.

Because the modification is a deletion, DES(1-3)IGF-1 and intact IGF-1 differ by about 283 Da — a clear separation at this molecular weight and easily resolved. But the direction matters: incomplete processing would leave intact IGF-1 in the preparation, and intact IGF-1 is heavier, not lighter. A mass figure reported as an average across a preparation could be pulled upward by residual full-length material without any single species being wrong.

The absence of an independently verifiable formula or CAS makes this compound harder to specify than the others documented here, which is worth weighing when assessing any supplier’s claims about it.

References

• Sara VR, Carlsson-Skwirut C, Andersson C, et al. Characterization of somatomedins from human fetal brain: identification of a variant form of insulin-like growth factor I. Proceedings of the National Academy of Sciences, 1986. PMID 3460078
• Francis GL, Upton FM, Ballard FJ, et al. Insulin-like growth factors 1 and 2 in bovine colostrum: sequences and biological activities compared with those of a potent truncated form. Biochemical Journal, 1988. PMID 3390164

Summary

IGF1-DES, properly DES(1-3)IGF-1, is insulin-like growth factor 1 lacking its N-terminal Gly-Pro-Glu tripeptide — 67 residues, approximately 7,370 g/mol by derivation from intact IGF-1. Those three residues contribute to IGF-binding protein recognition, so removing them releases the molecule from the system that normally holds most circulating IGF-1 inactive. It is therefore more active in tissue without being a stronger receptor agonist. It reaches that outcome by truncation where IGF1-LR3 uses extension, and unlike LR3 it occurs naturally, having been isolated from colostrum and brain tissue. Its identity data is less well documented than that of other compounds in this library. We do not stock it.

This page is provided for research reference. Compounds described in this library are for laboratory research use only, are not drugs, foods or cosmetics, and may not be used for any purpose other than in vitro or non-human laboratory research.