What is IPTG?
What is IPTG?
What is IPTG?
· IPTG (isopropyl-β-D-thiogalactopyranoside) is a synthetic, non-metabolizable analog of galactose that binds the lac repressor and lifts repression to induce β-galactosidase or any gene downstream of a lac-operator promoter in E. coli
· Because it cannot be cleaved by β-galactosidase, its cellular concentration remains constant throughout induction, offering reproducible control over gene expression
Mechanism of Action
· IPTG binds LacI repressor, triggering a conformational change that causes LacI to release the operator site.
· This derepression allows RNA polymerase and/or T7 RNA polymerase (in DE3 systems) to transcribe genes under lac-controlled or T7 promoter control
Applications
· Blue-white colony screening, working alongside X-Gal, Bluo-Gal, or MagentaGal for differential colony color based on presence or absence of β-galactosidase
· Recombinant protein induction, especially in E. coli BL21(DE3)/pET systems: IPTG addition induces T7 RNA polymerase and downstream gene of interest
· Timed gene activation for functional studies or synthetic biology circuits
Usage Protocols & Best Practices
· Storage: Powder stored desiccated at –20 °C. Stock solutions (e.g., 100 mM) should be filter-sterilized (0.22 μm) and aliquoted, stored at –20 °C, protected from light, and used within one year.
· Reconstitution: Dissolve 0.238 g in 10 mL sterile water to make 100 mM stock. Filter sterilize and aliquot (1 mL).
· Induction timing: Add IPTG at mid-log phase (OD₆₀₀ ≈ 0.4–0.6), for either fast induction at 37 °C over ~3–4 h or slow induction at ~20 °C for 12–16 h, depending on your expression and solubility needs.
· Concentration range: Typical working range is 0.1–1.0 mM, often optimized via a small-scale titration (e.g. 0.01 to 1 mM) followed by SDS-PAGE analysis. Higher IPTG may cause inclusion bodies.
Potential Side Effects & Limitations
· At higher IPTG concentrations, or in sensitive host strains, cell toxicity may occur. Lower IPTG levels or alternative induction methods (auto-induction media) can mitigate that risk.
· Inclusion bodies formation is more likely at high induction strength and temperature. Optimization of IPTG concentration and induction conditions is recommended.
Aladdin Scientific Products Related to IPTG
Aladdin Scientific offers UltraPure IPTG (≥99% purity) as its main product; they also provide solution and alternative formats. Based on product listings:
· Product codeI274316 — IPTG (Isopropyl-β-D-thiogalactopyranoside), ≥99% purity, CAS 367-93-1. Offered in sizes from 1 g to 100 g.
Additionally:
· IPTG solution (sterilized, 50 mg/mL) ，10mM in DMSO，product listed under I301904, I423647 .
Advantages of Aladdin's IPTG Products
· Ultra-pure grade (≥99%) suitable for sensitive molecular biology work.
· Certified quality: detailed CoA, SDS data provided.
· Prepared solutions available, saving time and reducing error risk.
· Different formats: solid powder and ready-to-use solution formats to suit different workflows.
· Sourcing transparency: argon-charged storage to minimize oxidation.
Summary
IPTG is a stable, effective inducer of lac-controlled gene expression, widely used in recombinant protein production and cloning workflows. It offers reliable concentration maintenance, minimal metabolic interference, and compatibility with blue–white screening assays. While safe when handled properly, laboratory safety protocols must be observed due to dust hazards and potential irritation. Aladdin Scientific’s IPTG product code I274316, I104812, I301904, I423647 provides a top-grade reagent with full documentation and flexible sizing, making it a suitable choice for research labs of all scales.
Aladdinsci: https://www.aladdinsci.com