IGF-1 LR3: Handling, Storage, and Reconstitution Guide

IGF-1 LR3 is an 83-residue recombinant protein, not a short synthetic peptide. That fact drives nearly every handling choice a lab makes with it. A molecule of about 9,117 g/mol has a folded structure. Heat, shear, sticking to surfaces, and repeated freezing can all damage it. None of these are pressing concerns for a ten-residue peptide. This guide covers lab practice for storing, reconstituting, aliquoting, and recording the material for in vitro prep.

Why does IGF-1 LR3 handling differ from short peptide work?

IGF-1 LR3 behaves like a small protein, so it needs protein-style handling. It is also listed as Long R3 IGF-1, LR3-IGF-1, Long Arg3 IGF-1, or IGF1-LR3. It is a modified analog of human insulin-like growth factor-1.

It has an arginine in place of glutamic acid at the third position. It also has 13 extra amino acids at the N-terminus, which bring the chain to 83 residues. Its reported formula is C400H625N111O115S9. Its molecular weight is near 9117.60 g/mol, and its CAS number is 946870-92-4.

At that size, three risks stand out:

• Surface sticking removes a larger share of it at the low concentrations used in receptor signaling assays.
• Shear and foam from vortexing can cause partial unfolding.
• Every freeze-thaw cycle invites clumping that no later care will reverse.

The analog was built to bind less to IGF-binding proteins, as described in the IGF-1 LR3 mechanism of action. That trait concerns how much reaches the receptor. It says nothing about physical stability in a vial. So handling rules should come from protein practice, not peptide practice.

What should labs confirm before opening an IGF-1 LR3 vial?

Good handling starts with checks, not with a solvent. Confirm that the label, lot number, and format match the supplied records. Check that the contents look like an intact, white, freeze-dried cake.

• Appearance: solid, white lyophilized powder in a sealed glass vial.
• Molecular weight: about 9117.60 g/mol, used for all molar math.
• Formula C400H625N111O115S9, CAS 946870-92-4.
• Formats of 0.1 mg and 1 mg, at a stated purity of 99 percent or greater.

Puritide Research is a supplier, not a producer. The material is US-made. It is prepared by a domestic synthesis partner and released against independent third-party testing. Current batch records are on the IGF-1 LR3 product page.

How should lyophilized IGF-1 LR3 be stored?

Store lyophilized IGF-1 LR3 sealed at 25 degrees Celsius or below, away from heat, light, and moisture. For long holding, keep it lyophilized and refrigerated or frozen. The dry state is by far the most stable form of this compound. So leave it dry until a test needs a stock.

Moisture is the quiet failure mode. A freeze-dried cake pulls water from the air. A vial moved straight from cold storage into a warm room will collect water on the powder as soon as the stopper is opened.

Three habits help:

• Let sealed vials reach room temperature before opening.
• Keep vials dry with a desiccant.
• Avoid frost-free freezers, whose defrost cycles warm their contents again and again.

Which solvent and technique suit IGF-1 LR3 reconstitution?

Lyophilized material is reconstituted with bacteriostatic water or another solvent that suits the planned assay. Proteins in the IGF-1 family are usually first dissolved in a mildly acidic diluent, such as dilute acetic acid. They are then diluted into the buffered medium the assay calls for. This is because they dissolve better away from neutral pH.

Follow the solvent guidance supplied with the lot. Keep the choice the same so solvent is never a hidden variable.

The technique is simple:

1. Add diluent slowly down the inner wall, not directly onto the cake.
2. Let the vial stand for ten to twenty minutes.
3. Swirl gently to finish dissolving. Do not vortex or shake.
4. Hold the stock up to a light. Discard anything cloudy or with particles.

Concentration math rests on the labeled mass and a molecular weight of about 9117.60 g/mol. So a 0.1 mg vial in 1 mL gives a nominal 100 micrograms per mL. That is close to 11 micromolar. Check content against the certificate of analysis before relying on a stock as quantitative.

Why use carrier protein and low-binding labware with IGF-1 LR3?

Working concentrations for IGF-1 receptor assays often sit in the low nanomolar or sub-nanomolar range. At those levels, a protein this size is lost to container walls. The loss is large enough to shift the applied concentration.

• Carrier protein, most often albumin at about 0.1 percent, in the buffer used for low-concentration dilutions.
• Low-binding polypropylene tubes and low-retention tips at every dilution step, not glass or standard polystyrene.
• Carrier use, or its absence, recorded in the protocol, since it affects total-protein assays.

There is one exception. Added albumin interferes with total-protein tests. It also interferes with some mass-spectrometry and immunoassay workflows. So a carrier-free dilution is sometimes the right call. In that case, keep transfer steps to a minimum. Record surface loss as a known limitation.

How should IGF-1 LR3 be aliquoted to limit freeze-thaw?

Reconstituted IGF-1 LR3 is much less stable than the dry powder. So split the stock into single-use aliquots as soon as it dissolves. Size them so no tube is opened twice. Repeated freeze-thaw cycles are the most common avoidable cause of protein breakdown.

Label every aliquot with compound, lot, concentration, solvent, and date. Thaw on ice, not at room temperature. Use it promptly, and do not refreeze an opened tube.

Keep reconstituted material cold within the window the lab protocol sets. The same logic applies across this category, as set out in the Tesamorelin handling and reconstitution guide.

What does the IGF-1 LR3 certificate of analysis confirm?

Every batch ships with a third-party-verified certificate of analysis. It records:

• Purity by HPLC or reverse-phase chromatography.
• Identity by mass spectrometry.
• Lot number, test date, and method.

For a recombinant analog this complex, the mass-spectrometry check matters most. It is what tells the intended 83-residue construct apart from a truncated, or shortened, product. So it is worth reading, not just filing.

Sample certificates can be requested before purchase. Outside checks are encouraged where a lab has the testing capacity. Record the lot against every test so results stay traceable to a batch. The same habit applies to the compounds in the Follistatin handling and storage guide. Prep quality feeds straight into the assay designs in the IGF-1 LR3 research applications.

What are common questions about handling IGF-1 LR3?

Can IGF-1 LR3 be reconstituted with plain sterile water?

Sterile or bacteriostatic water works for many peptide stocks. But IGF-1 family proteins are usually dissolved first in a mildly acidic diluent, then diluted into assay buffer. Follow the guidance supplied with the lot. Keep the choice the same across every arm of a study.

How many freeze-thaw cycles are acceptable for a reconstituted stock?

The safe answer is one. Each cycle is a chance for clumping that cannot be undone. So standard practice is to aliquot into single-use volumes and discard rather than refreeze. If a stock must be reused, record the cycle count with the data.

Does carrier protein need to be added to every dilution?

Not always, but it should be the default for low-concentration dilutions. That is where loss to tube walls is largest. The exception is any readout that added albumin disturbs, such as total-protein tests. In that case, make dilutions right before use and record the omission.

For research use only. IGF-1 LR3 is an investigational research material and is not approved for human or veterinary use. All handling described here refers to laboratory preparation for in vitro and preclinical research.