How to Reconstitute IGF-1 LR3: Laboratory Preparation Guide for Research IGF-1 LR3 (Long R3 IGF-1, MW ~9117 Da) is a recombinant 83-amino acid IGF-1 analogue incorporating an N-terminal 13-amino acid extension and Glu3→Arg3 substitution that reduce IGFBP binding affinity by approximately 1000-fold while maintaining IGF-1 receptor binding. It is supplied as a lyophilised powder in a 10mL sterile glass vial containing 1mg of peptide. Due to its large molecular weight and protein-like structure, IGF-1 LR3 requires specific reconstitution considerations to maintain biological activity in cell model research applications. Materials Required IGF-1 LR3 1mg lyophilised vial Sterile 0.1% acetic acid or sterile water for reconstitution Sterile PBS or cell culture media for further dilution 0.5mL or 1mL sterile syringe with needle Alcohol swabs (70% isopropyl) Nitrile gloves Permanent marker for labelling Refrigerator at 2–8°C for storage Important Note on Solvent Selection IGF-1 LR3 differs from smaller synthetic peptides in that it is most stably reconstituted in sterile 0.1% acetic acid rather than BAC water. The slightly acidic pH maintains protein conformation and prevents aggregation at the stock concentration. When preparing working dilutions for cell model assays, always dilute the acetic acid stock into PBS, serum-free media, or BSA-containing buffer (0.1% BSA in PBS) to neutralise the pH before adding to cells — do not add the acetic acid stock directly to cell culture media without dilution. Step-by-Step Reconstitution Protocol Step 1 — Prepare workspace. Wipe work surface with 70% isopropyl alcohol. Allow to dry. Wear nitrile gloves throughout. Step 2 — Swab vial stopper. Clean the rubber stopper of the IGF-1 LR3 vial with a fresh alcohol swab. Air dry for 10 seconds. Step 3 — Draw 0.5mL of sterile 0.1% acetic acid. Using a sterile syringe, draw 0.5mL of sterile 0.1% acetic acid. This yields a stock concentration of 2mg/mL (2000mcg/mL). Step 4 — Inject very slowly along the vial wall. Direct the acetic acid solution slowly down the inner glass wall of the IGF-1 LR3 vial over 15–20 seconds. IGF-1 LR3 is a protein-class molecule — slower, gentler reconstitution reduces the risk of protein denaturation. Step 5 — Dissolve by very gentle swirling. Gently swirl the vial for 30–60 seconds. Do not shake, vortex, or agitate vigorously. IGF-1 LR3 should dissolve to produce a clear, colourless solution. If the solution appears cloudy, allow it to stand at 4°C for 10 minutes and re-inspect before discarding. Step 6 — Label. Record reconstitution date, concentration, solvent used, and initials. Resulting Concentration and Dilution Adding 0.5mL sterile 0.1% acetic acid to a 1mg IGF-1 LR3 vial yields a stock concentration of 2mg/mL (2000mcg/mL). For IGF-1R activation assays in C2C12 myocyte or MCF-7 cell model preparations, dilute the acetic acid stock at least 1:100 into PBS + 0.1% BSA before further serial dilution to working concentrations of 1ng/mL–1mcg/mL. Concentration Reference Table Acetic Acid Volume AddedResulting Concentration 0.5mL2.0mg/mL (2000mcg/mL) 1.0mL1.0mg/mL (1000mcg/mL) Storage Conditions and Stability Store lyophilised IGF-1 LR3 at −20°C or −80°C for long-term storage, protected from light and moisture. Once reconstituted, store at 2–8°C. Reconstituted IGF-1 LR3 in 0.1% acetic acid is stable for up to 14 days under refrigeration — shorter than BAC water-reconstituted peptides due to the absence of benzyl alcohol preservative. Add 0.1% BSA as a carrier protein to extend stability. Avoid repeated freeze-thaw cycles. For long-term working aliquot storage, prepare single-use aliquots in 0.1% BSA/PBS and store at −80°C. Research Application Notes IGF-1 LR3's defining advantage over native IGF-1 in cell model research is its >1000-fold reduced IGFBP affinity — in serum-containing media where IGFBPs are present, IGF-1 LR3 maintains effective IGF-1R receptor engagement while native IGF-1 is substantially sequestered. Always include a 0.1% BSA/PBS vehicle control in cell model assays to account for the carrier protein and neutralised acetic acid dilution vehicle. IGF-1 LR3 1mg vials are available from Pinnacle Peptides, verified at ≥99% purity by HPLC and mass spectrometry. All content is intended for in vitro laboratory research purposes only. Not for human or animal consumption. Not intended to diagnose, treat, cure, or prevent any condition.