Peptide Reconstitution Guide¶
1. Step-by-Step Reconstitution Protocol¶
Step 1: Equilibration Remove the lyophilized vial from -20°C storage. Allow to equilibrate to room temperature for 15–30 minutes without opening. This prevents moisture condensation on the lyophilized cake.
Step 2: Calculation Calculate the required solvent volume:
Target Concentration (mg/mL) = Peptide Mass (mg) / Solvent Volume (mL)
Volume (mL) = Peptide Mass (mg) / Target Concentration (mg/mL)
For molarity:
Molarity (M) = Concentration (mg/mL) / Molecular Weight (g/mol)
Step 3: Solvent Addition 1. Sterilize vial septum with 70% ethanol wipe 2. Use a sterile syringe and needle 3. Add solvent gently along the inner wall of the vial 4. Do NOT inject directly onto the lyophilized cake 5. Remove needle and cap securely
Step 4: Dissolution 1. Gently swirl or invert the vial 2. Let stand for 5–10 minutes 3. Visually inspect — solution should be clear with no visible particles 4. If incomplete dissolution, gently warm to 25°C or sonicate briefly (30 sec water bath)
Step 5: Aliquoting 1. Prepare labeled, low-binding microcentrifuge tubes 2. Dispense single-use volumes (10–50 µL) 3. Snap-freeze in liquid nitrogen (optional, for >6 month storage) 4. Store at -20°C
2. Recommended Diluent Selection¶
| Diluent | pH | Best For | Notes |
|---|---|---|---|
| Sterile WFI | 5–7 | Most peptides | First choice; minimal interference |
| PBS (1×) | 7.4 | Cell culture assays | Physiological osmolarity |
| 0.9% Saline | 5.5 | In vivo injections | Isotonic |
| 10 mM Acetic Acid | 3.5 | Basic/hydrophobic peptides | Improves solubility |
| 0.1% DMSO in PBS | — | Hydrophobic stock solutions | Keep DMSO ≤0.1% final |
3. Reconstitution Troubleshooting¶
| Problem | Likely Cause | Solution |
|---|---|---|
| Cake won't dissolve | Lyophilized cake too compact | Add more solvent; increase incubation time; warm to 25°C |
| Solution cloudy | Aggregation or precipitation | Dilute further; adjust pH; add co-solvent |
| Gel formation | High concentration, β-sheet formation | Reduce concentration; add denaturant (6 M urea) compatible with assay |
| Foaming | Surfactant-like peptide sequence | Let settle before aliquoting; avoid pipetting air |
| Loss of activity | Degradation or aggregation | Verify storage; use fresh aliquot; check pH |
4. Important Notes¶
- Always record: batch number, date reconstituted, solvent used, final concentration, aliquoting volume
- Use low-binding tubes and pipette tips to minimize surface adsorption
- Do not vortex peptide solutions at any stage
- Do not subject to repeated freeze-thaw cycles (> 3×)
- For long-term storage of reconstituted peptides, snap-freeze aliquots in liquid nitrogen
For reconstitution inquiries: [email protected]