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Long R3 IGF-1 vs IGF-1 LR3: Structural Comparison
Amino Acid Length 83 residues 70 residues The 13-residue N-terminal extension in Long R3 is the primary structural modification. Not a post-translational addition but a designed sequence extension Position 3 Residue Arginine (Arg) Glutamic Acid (Glu) This sing
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- Amino Acid Length
- 83 residues
- 70 residues
- The 13-residue N-terminal extension in Long R3 is the primary structural modification. Not a post-translational addition but a designed sequence extension
- Position 3 Residue
- Arginine (Arg)
- Glutamic Acid (Glu)
- This single substitution reduces IGFBP-3 binding affinity by 10–20-fold, critical for extended in vitro stability
- IGFBP Binding Affinity
- Reduced 100-fold vs native IGF-1
- High affinity for all six IGFBPs
- The functional consequence: Long R3 remains bioavailable in serum-containing media where native IGF-1 would be sequestered within minutes
- Functional Half-Life (cell culture)
- 15–20 hours
- <10 minutes
- This allows once-daily dosing in multi-day protocols without media replacement. Native IGF-1 requires dosing every 2–4 hours
- IGF-1 Receptor Affinity
- Equivalent to native IGF-1
- Baseline (100%)
- The structural modifications do not reduce receptor engagement. Signaling potency remains unchanged
- CAS Registry Number
- 946870-92-4
- 67763-96-6
- Use CAS numbers for definitive product verification. Naming conventions vary, molecular structure does not