IGF1-LR3

IGF1-LR3, Long R3 IGF-1, is an 83-residue analogue of insulin-like growth factor 1. Native IGF-1 is 70 residues, so this is a substantially larger molecule than the peptides elsewhere in this catalogue and closer to a small protein.

It differs from the native sequence in two documented ways: an arginine substituted for glutamate at position 3, which is the R3 in the name, and a 13-residue extension at the N-terminus, which is the Long. The arginine substitution markedly reduces affinity for IGF binding proteins, and that reduced binding is the property the analogue was designed around.

At 83 residues it is supplied at 1mg per vial rather than the 5 to 60mg typical of shorter peptides, which is a direct consequence of molar mass rather than a difference in presentation.

Supplied as a lyophilised (freeze-dried) powder in a sealed vial under vacuum. Lyophilisation removes water by sublimation, which is what allows a peptide to remain stable at ambient temperature during transit where a solution would degrade.

Reconstitution in a laboratory setting is typically performed with bacteriostatic water, introduced slowly against the vial wall rather than directly onto the powder cake. Peptide bonds are susceptible to shear, so the vial is swirled to dissolve rather than shaken.

Lyophilised and sealed, the vial is stable at 2 to 8 degrees Celsius and tolerates ambient temperature in transit. For storage beyond several months, minus 20 degrees Celsius is standard.

Once in solution the stability window shortens considerably and refrigeration is required. Repeated freeze-thaw cycles are the most common cause of degradation in a reconstituted peptide, so solutions are generally aliquoted rather than frozen and thawed as a single volume.

Every batch is independently tested through seven rounds of analysis. Identity is confirmed by mass spectrometry and purity quantified by reverse-phase HPLC, with the resulting Certificate of Analysis published against the specific batch rather than the product line.

Testing is performed by third-party laboratories operating to ISO 17025. The COA for the batch currently shipping is linked from this page and archived at /lab-tests.