How to Reconstitute Fragment 176-191: Laboratory Reconstitution Protocol
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How to Reconstitute Fragment 176-191: Laboratory Reconstitution Protocol
Fragment 176-191 (HGH Frag 176-191, MW 1817.12 g/mol, CAS 66004-57-7) is a synthetic peptide corresponding to amino acids 176–191 of human growth hormone, studied in vitro for its interactions with adipocyte beta-3 adrenergic receptor pathways and lipolysis signalling in fat cell model systems. It is supplied as a lyophilised white powder in a 10mL sterile glass vial containing 5mg of peptide.
Materials Required
- Fragment 176-191 5mg lyophilised vial
- Bacteriostatic water (BAC water) — 10mL vial
- 1mL sterile syringe with needle
- Alcohol swabs (70% isopropyl)
- Nitrile gloves
- Permanent marker for labelling
Pre-Reconstitution Preparation
Inspect the vial to confirm intact lyophilised powder and an unbroken seal. Allow to equilibrate to room temperature for 10–15 minutes before reconstitution. Fragment 176-191 contains several hydrophobic residues in the C-terminal GH sequence — room temperature equilibration facilitates complete dissolution at the stock concentration.
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 both stoppers. Clean rubber stoppers on both vials with separate fresh alcohol swabs. Air dry 10–15 seconds.
Step 3 — Draw 2mL of BAC water. Draw 2mL of bacteriostatic water into a sterile syringe.
Step 4 — Inject slowly along the vial wall. Direct the BAC water slowly down the inner glass wall of the Fragment 176-191 vial over 15–20 seconds. The C-terminal hydrophobic sequence makes wall-directed injection particularly important for this peptide.
Step 5 — Dissolve by gentle swirling. Swirl gently for 30–60 seconds. Fragment 176-191 dissolves well in BAC water, though may require slightly more swirling than smaller hydrophilic peptides. The solution should be clear to very slightly opalescent. Do not shake or vortex.
Step 6 — Inspect and label. Confirm clarity. Label with reconstitution date, concentration, and initials.
Resulting Concentration
Adding 2mL BAC water to a 5mg Fragment 176-191 vial yields a stock concentration of 2.5mg/mL (2500mcg/mL). For adipocyte cell model studies in 3T3-L1 preparations, working concentrations of 1ng/mL to 10mcg/mL are prepared by serial dilution into serum-free media.
Concentration Reference Table
| BAC Water Volume Added | Resulting Concentration |
|---|---|
| 1mL | 5.0mg/mL |
| 2mL | 2.5mg/mL (2500mcg/mL) |
| 5mL | 1.0mg/mL (1000mcg/mL) |
Storage Conditions and Stability
Store lyophilised Fragment 176-191 at −20°C prior to reconstitution, protected from light. Once reconstituted, store at 2–8°C. Reconstituted Fragment 176-191 in BAC water is stable for up to 28 days under refrigeration. Do not freeze reconstituted solution. Prepare single-use aliquots at −80°C for long-term working stock storage.
Troubleshooting Common Reconstitution Issues
Powder not dissolving: Gently tilt and swirl the vial to bring undissolved powder into contact with the solvent. Do not heat. If dissolution remains incomplete after 60 seconds of swirling, inspect for moisture ingress or compromised seal.
Cloudy solution: Cloudiness may indicate aggregation, contamination, or particulate matter. Discard if cloudiness persists after gentle swirling and re-inspection.
Foaming: Allow foam to settle naturally. Reduce injection speed and ensure the stream is directed along the glass wall on subsequent attempts.
Loss of material: Swirl the vial to contact all inner surfaces. For maximum recovery, invert and draw from the stopper end after complete dissolution.
Research Application Notes
Fragment 176-191 is studied in adipocyte cell model systems for its beta-3 adrenergic receptor-associated lipolysis pathway interactions, independent of the insulin-like growth factor axis that characterises full-length GH pharmacology. In 3T3-L1 adipocyte cell model applications, lipolysis endpoint assays measuring glycerol release and HSL phosphorylation provide functional readouts linked to beta-3 AR pathway engagement. Include isoproterenol (a non-selective beta-AR agonist) and SR59230A (beta-3 AR selective antagonist) as positive and negative pharmacological controls respectively to confirm receptor pathway attribution. Fragment 176-191 5mg 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.
