Preparation IPTG Stock Solution
This guide describes the preparation of IPTG Stock Solution at a defined molarity for laboratory use.
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Stock Solution Preparation Guide – IPTG
IPTG (Isopropyl β-D-1-thiogalactopyranoside) is a lactose analog widely used in molecular biology to induce the expression of recombinant proteins in E. coli under the control of lac or tac promoters. IPTG binds to the lac repressor, releasing it from the lac operator and allowing transcription of downstream genes. It is also used for blue/white selection in cloning.
Chemical Information
| Name | Molecular Formula | Molecular Weight | CAS |
|---|---|---|---|
| IPTG | C₉H₁₈O₅S | 238.3 g/mol | 367-93-1 |
Applications
- Induction of protein expression in E. coli
- Identification of positive clones by blue/white selection
Solubility and Handling
- IPTG is supplied as a white crystalline powder that dissolves readily in water.
- Prepare stock solutions using nuclease-free water and sterile techniques.
- Never autoclave IPTG solutions; heat can degrade the compound.
Stock Solution Preparation
To prepare a 1 M IPTG stock solution:
Weigh 2.38 g of IPTG powder and add to ~8 mL of deionized water.
Mix until completely dissolved.
Add deionized water to a final volume of 10 mL and mix thoroughly.
Mix until completely dissolved.
Add deionized water to a final volume of 10 mL and mix thoroughly.
Sterilization and Storage
- Sterilize by filtering through a 0.22 µm filter into a sterile container.
- Aliquot the stock into small volumes (e.g., 0.5–1 mL) to avoid repeated freeze–thaw cycles.
- Store aliquots at −20 °C for long-term use.
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