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IGF-1 DES Disposable Self-injection Pen is a pre-filled device holding des(1-3) IGF-1, the native protein with its first three residues removed.
– 67 residues rather than 70, missing the N-terminal glycine-proline-glutamate tripeptide
– GPE is cleaved from IGF-1 in tissue anyway, so the truncated form occurs naturally
– LR3 extends the protein where DES shortens it. Both end up binding IGFBPs less tightly
– Solution-state folded protein, so aggregation and disulfide scrambling are the handling risks · lot-specific COA
Research use only. Not for human or veterinary use, food, or household application.
Epic Peptides Lab · Research Use Only
DES(1-3) IGF-1 · 67 residues · pre-filled device
IGF-1 DES Disposable Self-injection Pen is a pre-filled device supplying DES(1-3) IGF-1, a 67-residue truncated analogue of insulin-like growth factor 1. The designation indicates removal of the first three residues, glycine, proline and glutamate, from the amino terminus of the 70-residue native sequence.
| Property | Value |
|---|---|
| Compound | DES(1-3) IGF-1 |
| Common designation | IGF-1 DES |
| Parent molecule | Insulin-like growth factor 1, 70 residues |
| Residue count | 67 |
| Modification | Removal of residues 1 to 3 from the amino terminus |
| Residues removed | Glycine-Proline-Glutamate (GPE) |
| Approximate molecular weight | 7371 Da |
| Disulfide bonds | Three, as in native IGF-1 |
| Molecular target | IGF-1 receptor (IGF1R), a receptor tyrosine kinase |
| Effect of truncation | Substantially reduced affinity for IGF binding proteins |
| Natural occurrence | Reported as a naturally occurring form in some tissues |
| Relationship to GPE | The removed tripeptide has been studied separately as a distinct compound |
| Format | Pre-filled Disposable Self-injection Pen device |
| Physical state | Solution, supplied ready-filled |
| Appearance | Clear colourless solution |
| Purity | Per lot-specific certificate of analysis |
| Storage | 2-8°C, protected from light. Do not freeze the device |
| Regulatory status | No approved human or veterinary formulation in any jurisdiction |
The IGF-1 DES Disposable Self-injection Pen supplies a protein missing three residues from seventy is a small change by mass and a large one by function, which makes the reason worth examining.
The amino-terminal region of IGF-1 participates directly in the binding protein interface. Glutamate at position 3 in particular contributes an acidic contact that IGF binding proteins recognise, and removing it eliminates that contact rather than merely weakening it.
Note the convergence with the LR3 analogue, which modifies the same position by substitution rather than deletion. Two different chemical strategies aimed at the same residue, arrived at independently, which is reasonable evidence that position 3 genuinely matters for binding protein association.
Receptor binding is comparatively less affected, because the receptor contact surface involves different regions of the molecule. The truncated protein retains the three disulfide bonds and the overall fold that receptor binding depends on.
The removed tripeptide, glycine-proline-glutamate, has been studied as a compound in its own right, which is an unusual situation where both the fragment and the remainder attract separate research attention.
Both analogues address binding protein affinity, and choosing between them depends on what a design needs to hold constant.
DES(1-3) is smaller than native IGF-1, at 67 residues against 70, while LR3 is larger at 83, because it adds an extension as well as substituting. Molecular weight differs accordingly, roughly 7371 against roughly 9111 daltons.
That weight difference matters for molar calculation. Two preparations at the same mass concentration contain substantially different molar concentrations, and comparing analogues on a mass basis rather than a molar basis introduces an error of over twenty percent.
DES(1-3) is reported to occur naturally in some tissues, whereas LR3 is entirely synthetic with no natural counterpart. For work concerned with physiological relevance that distinction may matter.
LR3 carries a larger structural alteration, with thirteen added residues representing a substantial addition to a small protein, and whether that extension affects anything beyond binding protein association is a question a DES comparison can help answer.
Running both analogues in parallel is more informative than either alone where the question concerns binding protein contribution.
A pre-filled device holds this protein in solution continuously, and the degradation routes available to a folded protein differ from those affecting short peptides.
Aggregation is the principal concern. Partially unfolded molecules expose hydrophobic surfaces that normally sit buried in the core, and those surfaces associate with each other. The process is self-accelerating, since aggregates nucleate further aggregation, and it is effectively irreversible.
Disulfide scrambling is the second route. Three disulfide bonds define the fold, and under circumstances permitting thiol-disulfide exchange those bonds can reform in incorrect pairings. The rearranged molecule has the same mass and a different structure, which makes the change invisible to mass spectrometry.
Surface adsorption removes protein from solution onto container walls, disproportionately at low concentration, and deamidation and oxidation also proceed, though more slowly than aggregation under typical storage.
Air-liquid interfaces accelerate unfolding, which is why agitation is specifically discouraged. Every bubble generated presents a surface at which protein molecules unfold.
A sealed solution-state protein device limits verification, and knowing what remains available is worth establishing before the material is needed.
Visual inspection carries real information here, more than for a small molecule. The solution should be clear and colourless. Cloudiness, opalescence or visible particulate indicates aggregation and disqualifies the unit, since aggregated protein has lost the fold determining its activity.
The certificate of analysis should state protein concentration determined analytically, purity by a method appropriate to proteins such as size-exclusion chromatography, and the absence of aggregate. Size-exclusion is specifically useful because it detects soluble aggregates that visual inspection cannot.
Manufacture date matters for the same reason it matters for solution-state NAD+, though the mechanism differs. Aggregation accumulates with time in solution, and a recently manufactured device has had less opportunity for it.
Storage history during transit should be documented. A cold-chain excursion is more consequential for a folded protein than for most compounds, because that aggregation does not reverse when temperature is restored.
The three residues removed to produce this analogue have an independent research history, which is unusual and worth knowing about.
Glycine-proline-glutamate, abbreviated GPE, is the amino-terminal tripeptide of IGF-1. When the parent protein is cleaved to produce the truncated form, the tripeptide is released as a separate molecule rather than degraded immediately.
GPE has been studied in its own right, principally in neural contexts, and reported not to act through the IGF-1 receptor. Its proposed interactions involve other systems entirely, which means the cleavage produces two molecules with different targets rather than one active molecule and one waste product.
The experimental implication is direct. In any system where the parent protein is subject to amino-terminal cleavage, both products are present, and an observed effect could originate from either.
Supplying the truncated form removes that ambiguity from the design. The tripeptide is simply absent, so anything observed is attributable to the 67-residue species.
Conversely, comparing the truncated form against the intact parent in a cleaving system does not isolate the truncation, because the parent condition also generates the tripeptide. Running GPE as a third arm resolves it.
The disulfide architecture is what makes this a folded protein rather than a flexible chain, and it sets several handling boundaries.
Three bonds in a 67-residue protein is a high density, and they cross-link the chain into a compact fold. The insulin-like architecture is stabilised almost entirely by these bonds rather than by an extensive hydrophobic core.
Reducing agents are therefore excluded. Dithiothreitol, beta-mercaptoethanol and tris(2-carboxyethyl)phosphine will break the bonds, and the protein does not refold correctly afterward without controlled oxidative conditions.
That matters because reducing agents appear routinely in buffers for other purposes, including protease inhibition and protection of unrelated proteins in a lysate. A buffer chosen for a downstream step can inactivate the growth factor before it acts.
Free thiols in the system present the same hazard through disulfide exchange, which can occur even without a formal reducing agent present when cysteine-containing proteins are abundant.
Checking buffer composition for reducing agents before adding this protein is a small step that spares an entire experiment from a false negative.
Documentation for a solution-state protein carries one field that dominates all the others.
Storage history, including every temperature excursion and its duration. Aggregation is irreversible, so an excursion three weeks ago still affects the material today, and no subsequent handling undoes it.
Beyond that, the standard fields apply: lot number, fill date, measured protein concentration with the method used, and purity by size-exclusion chromatography rather than by a method blind to soluble aggregate.
Visual condition at each use is worth logging rather than merely checking. A device that was clear on Monday and faintly hazy on Friday has told you something about its storage that a single pass-fail check would discard.
Where an IGF-1 DES Disposable Self-injection Pen is used across a series, note which experiments drew from which unit.
An IGF-1 DES Disposable Self-injection Pen wants cold, dark, still and unfrozen storage, inspected each time.
Maintain 2-8°C without interruption. Aggregation rate rises with temperature and the process does not reverse, so an ambient excursion has permanent consequences rather than temporary ones.
Never freeze. Ice formation concentrates solutes in the shrinking liquid phase and creates ice-water interfaces, and both drive aggregation efficiently. This applies to the device format regardless of how a bulk protein solution might be handled with cryoprotectant.
Handle gently. Do not shake, do not invert repeatedly, and avoid generating bubbles, because air-liquid interfaces unfold protein and mechanical agitation creates them.
Inspect for clarity before every use and reject any unit showing cloudiness or particulate. Record lot, manufacture date, storage history including any excursion, and dates of use.
One further point concerns temperature during use rather than during storage. A device removed from refrigeration warms quickly, and aggregation rate rises with temperature.
Where a session involves several sequential measurements, returning the device to cold between them rather than leaving it on the bench is worth the small inconvenience. The alternative is an hour at ambient temperature per session, accumulating across a study.
That accumulated warm time is rarely recorded and it is a plausible explanation for drift in a long series.
References verified against the publisher record. The IGF-1 analogue literature is well established and independent.
What is the IGF-1 DES Disposable Self-injection Pen?
A pre-filled device supplying DES(1-3) IGF-1, a 67-residue truncated analogue lacking the first three residues of the native 70-residue sequence. Those residues are glycine, proline and glutamate. It is supplied as a laboratory research reagent only, with no human or veterinary use.
Why does removing three residues matter so much?
Because the amino-terminal region participates directly in the binding protein interface. Glutamate at position 3 contributes an acidic contact that IGF binding proteins recognise, and removing it eliminates that contact rather than merely weakening it.
Is there a connection to the LR3 analogue?
Yes, and an informative one. LR3 modifies the same position by substitution rather than deletion. Two different chemical strategies aimed at the same residue, arrived at independently, is reasonable evidence that position 3 genuinely matters for binding protein association.
Does the truncation affect receptor binding?
Comparatively less, because the receptor contact surface involves different regions of the molecule. The truncated protein retains the three disulfide bonds and the overall fold that receptor binding depends on.
How do DES and LR3 compare by size?
DES(1-3) is 67 residues at roughly 7371 daltons. LR3 is 83 residues at roughly 9111 daltons. That difference means two preparations at the same mass concentration contain substantially different molar concentrations, an error of over twenty percent if compared by mass.
Does either occur naturally?
DES(1-3) is reported as a naturally occurring form in some tissues. LR3 is entirely synthetic with no natural counterpart, which is a distinction that may matter for work concerned with physiological relevance.
Why run both analogues in parallel?
Because LR3 carries a larger structural alteration, with thirteen added residues representing a substantial addition to a small protein, and whether that extension affects anything beyond binding protein association is a question a DES comparison helps answer.
What degradation routes affect a folded protein?
Aggregation principally, where partially unfolded molecules expose buried hydrophobic surfaces that associate with each other. The process is self-accelerating and effectively irreversible. Disulfide scrambling, surface adsorption, deamidation and oxidation also occur.
Why is disulfide scrambling hard to detect?
Because the rearranged molecule has the same mass as the correctly folded one, only with bonds reformed in incorrect pairings, and mass spectrometry cannot distinguish them, so detection requires methods sensitive to structure rather than to mass.
What should the certificate state?
Protein concentration determined analytically, purity by a protein-appropriate method such as size-exclusion chromatography, and absence of aggregate. Size-exclusion specifically detects soluble aggregates that visual inspection cannot see.
IGF-1 DES is sold exclusively for laboratory research use. It is not a drug, food, or cosmetic product, and it is not a dietary product of any kind. It is not approved by the FDA or any comparable authority for human or veterinary use, and the pre-filled device format does not alter that status in any way. This product is not intended to diagnose, treat, cure, or prevent any disease. It must not be given to humans or animals. Purchase is restricted to qualified researchers and institutions operating within applicable laws. All handling is the responsibility of the purchasing laboratory.
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