IPTG

Request Lot Specific COA

View Current Lot COA

Citation Search Tool

Description

IPTG is an analog of galactose that is non-metabolizable and inactivates the lac repressor to induce synthesis of β-galactosidase in E. coli. The expression of cloned genes under the control of the lac operon is induced by IPTG. It is also a substrate for thigalactoside transacetylase and has been reported to induce penicillinase in bacteria.

IPTG is commonly used in cloning procedures that require induction of β-galactosidase and is most often used with X-Gal (Gold Bio #X4281C) or Bluo-Gal (Gold Bio #B-673) for blue/white colony screening or Magenta-Gal (Gold Bio #B-378) for red/white colony screening of bacterial colonies.

IPTG is also used in the induction of recombinant proteins. In those systems, a protein of interest is encoded downstream of the IPTG inducible promoter. In the presence of IPTG, the protein of interest is induced in the cell culture. The culture can then be lysed and the protein expressed and purified through a number of methods, including His Tag or GST purification systems (for proteins with ligand tags).

GoldBio IPTG is made from a synthetic, non-animal origin.

 

Functional Highlights and Mechanism

  • IPTG acts by mimicking the natural inducer allolactose: it binds to the lac repressor (LacI) and causes its release from the lac operator site, allowing transcription of downstream genes under the lac promoter.

  • Because IPTG is not metabolized by the cell, its concentration remains stable over time, enabling sustained induction rather than being depleted. 

  • In recombinant protein expression systems (for example vectors using T7 promoter under lac operon regulation), addition of IPTG triggers expression of the gene of interest downstream of the inducible promoter. 

  • IPTG is often used in colony screening (e.g., blue/white screening) in combination with chromogenic substrates such as X‑Gal: in this context IPTG activates β-galactosidase expression which cleaves X-Gal to yield a colored product. 

  • Because of the consistency and high quality of GoldBio’s IPTG, it supports reproducible gene induction workflows and reduces variability associated with induction reagent quality.

 

Applications

  • Gene expression induction in systems controlled by the lac operon
  • Blue-white screening (with X-Gal) for recombinant DNA identification
  • Controlled production of recombinant proteins
  • Timed gene activation for functional studies
  • Regulatory input in synthetic biology circuits

Research Applications for IPTG

(Click each for more information)

Induction of Protein Expression in Lac Operon-Based Systems
  • Purpose: To induce recombinant protein expression in bacterial systems, particularly Escherichia coli.
  • How It Works: IPTG is a non-metabolizable analog of allolactose that binds to the LacI repressor, causing dissociation from the lac operator and activation of transcription from lac-derived promoters.
  • Applications: High-yield recombinant protein production using pET, pGEX, pMAL, and related expression systems.

Studier, F. W., & Moffatt, B. A. (1986). Use of bacteriophage T7 RNA polymerase to direct selective high-level expression of cloned genes. Journal of Molecular Biology, 189(1), 113–130.

Blue/White Screening in Cloning
  • Purpose: To differentiate recombinant clones from non-recombinant colonies during cloning workflows.
  • How It Works: IPTG induces β-galactosidase expression; in the presence of X-gal, colonies with intact lacZα appear blue, while recombinant colonies with disrupted lacZ remain white.
  • Applications: Screening workflows using pUC19, pBluescript, and other multiple cloning site-containing vectors.

Vieira, J., & Messing, J. (1982). The pUC plasmids, an M13mp7-derived system for insertion mutagenesis and sequencing with synthetic universal primers. Gene, 19(3), 259–268.

Study of Gene Regulation and Promoter Function
  • Purpose: To investigate transcriptional regulation and promoter-controlled gene expression.
  • How It Works: IPTG induces reporter genes such as GFP or luciferase downstream of lac-based promoters, enabling quantitative analysis of promoter activity and regulatory dynamics.
  • Applications: Promoter mapping, transcriptional dynamics studies, functional genomics, and educational laboratory assays.

Zaslaver, A., Bren, A., Ronen, M., Itzkovitz, S., Kikoin, I., Shavit, S., ... & Alon, U. (2006). A comprehensive library of fluorescent transcriptional reporters for Escherichia coli. Nature Methods, 3(8), 623–628.

Metabolic Engineering and Pathway Control
  • Purpose: To enable temporal regulation of enzyme expression in engineered metabolic pathways.
  • How It Works: Genes encoding pathway enzymes are placed under lac-derived promoters, allowing controlled pathway activation and metabolic flux modulation through IPTG induction.
  • Applications: Production optimization for biofuels, amino acids, polymers, and specialty chemicals in engineered microbial systems.

Zhang, F., Carothers, J. M., & Keasling, J. D. (2012). Design of a dynamic sensor-regulator system for production of chemicals and fuels derived from fatty acids. Nature Biotechnology, 30(4), 354–359.

Conditional Gene Expression in Synthetic Biology
  • Purpose: To provide external control over synthetic gene circuits and regulatory networks.
  • How It Works: LacI-IPTG regulatory modules function as tunable switches, repressors, or oscillators within engineered biological systems.
  • Applications: Synthetic circuit design, biosensor development, microbial consortia regulation, and educational synthetic biology platforms.

Elowitz, M. B., & Leibler, S. (2000). A synthetic oscillatory network of transcriptional regulators. Nature, 403(6767), 335–338.

 

Reconstitution

100mM IPTG stock solution

  1. Weigh 0.238 g of IPTG
  2. Add 10 mL sterile H2O. Dissolve completely.
  3. Prewet a 0.22 µm syringe filter by drawing through 5-10 mL of sterile H2O and discard water.
  4. Sterilize IPTG Stock through the prepared 0.22 µm syringe filter.
  5. Store in 1 mL aliquots at -20°C for up to 1 year.

 

Storage/Handling

Store powder IPTG desiccated at -20°C. Protect from light.
For IPTG stock solution, store in 1 mL aliquots at -20°C for up to 1 year. IPTG is readily dissolved in sterile water.

 

FAQ

How does IPTG work?

IPTG, which is similar to the lactose metabolite allolactose, induces the lac operon by binding to the lac repressor. Once IPTG binds to the lac repressor, a conformational change occurs, causing the lac repressor to dissociate from the lac promoter. Once the lac repressor dissociates, RNA polymerase binds to the promoter to initiate expression.

How much IPTG should be used for expression/ What concentration of IPTG should be used for expression?

Most papers recommend using between 0.1-1.0mM IPTG for expression. However, the amount you should use depends on your proteins. However, it is best to run an IPTG titration with ranges between 0.01-1.0mM and compare using SDS-PAGE to determine the optimal concentration. Something to keep in mind is higher concentrations of IPTG can cause inclusion bodies.

Why should I use IPTG over lactose?

IPTG is non-metabolizable, so its concentration remains stable and doesn’t get consumed by the bacteria.

When should I add IPTG during culture growth?

You should usually add IPTG at the mid-log phase (OD600 ≈ 0.4–0.6) to ensure cells are healthy and dividing rapidly.

Do I need to autoclave IPTG?

No—filter sterilize only. IPTG is heat-sensitive and should not be autoclaved.

Does IPTG degrade over time?

IPTG is stable when stored properly (aliquoted at -20°C, protected from light), but repeated freeze-thaw cycles should be avoided.

Can IPTG be reused after thawing?

The best practice is to use single-use aliquots of IPTG. Do not refreeze IPTG leftovers to avoid degradation or contamination.

Can IPTG be toxic to cells?

IPTG can be toxic at high concentrations or in sensitive strains. Lowering the IPTG concentration or using auto-induction media can help.


IPTG Tutorial Videos


IPTG

View Sizes & Pricing

Catalog Number:
I2481C
CAS Number:
367-93-1
$27.00

For research use only. Not for food, drug, household, or cosmetic use.
Availability:
In stock
Shipping:
$14.99 Ground shipping (In continental US only.)

    Description

    IPTG is an analog of galactose that is non-metabolizable and inactivates the lac repressor to induce synthesis of β-galactosidase in E. coli. The expression of cloned genes under the control of the lac operon is induced by IPTG. It is also a substrate for thigalactoside transacetylase and has been reported to induce penicillinase in bacteria.

    IPTG is commonly used in cloning procedures that require induction of β-galactosidase and is most often used with X-Gal (Gold Bio #X4281C) or Bluo-Gal (Gold Bio #B-673) for blue/white colony screening or Magenta-Gal (Gold Bio #B-378) for red/white colony screening of bacterial colonies.

    IPTG is also used in the induction of recombinant proteins. In those systems, a protein of interest is encoded downstream of the IPTG inducible promoter. In the presence of IPTG, the protein of interest is induced in the cell culture. The culture can then be lysed and the protein expressed and purified through a number of methods, including His Tag or GST purification systems (for proteins with ligand tags).

    GoldBio IPTG is made from a synthetic, non-animal origin.

     

    Functional Highlights and Mechanism

    • IPTG acts by mimicking the natural inducer allolactose: it binds to the lac repressor (LacI) and causes its release from the lac operator site, allowing transcription of downstream genes under the lac promoter.

    • Because IPTG is not metabolized by the cell, its concentration remains stable over time, enabling sustained induction rather than being depleted. 

    • In recombinant protein expression systems (for example vectors using T7 promoter under lac operon regulation), addition of IPTG triggers expression of the gene of interest downstream of the inducible promoter. 

    • IPTG is often used in colony screening (e.g., blue/white screening) in combination with chromogenic substrates such as X‑Gal: in this context IPTG activates β-galactosidase expression which cleaves X-Gal to yield a colored product. 

    • Because of the consistency and high quality of GoldBio’s IPTG, it supports reproducible gene induction workflows and reduces variability associated with induction reagent quality.

     

    Applications

    • Gene expression induction in systems controlled by the lac operon
    • Blue-white screening (with X-Gal) for recombinant DNA identification
    • Controlled production of recombinant proteins
    • Timed gene activation for functional studies
    • Regulatory input in synthetic biology circuits

    Research Applications for IPTG

    (Click each for more information)

    Induction of Protein Expression in Lac Operon-Based Systems
    • Purpose: To induce recombinant protein expression in bacterial systems, particularly Escherichia coli.
    • How It Works: IPTG is a non-metabolizable analog of allolactose that binds to the LacI repressor, causing dissociation from the lac operator and activation of transcription from lac-derived promoters.
    • Applications: High-yield recombinant protein production using pET, pGEX, pMAL, and related expression systems.

    Studier, F. W., & Moffatt, B. A. (1986). Use of bacteriophage T7 RNA polymerase to direct selective high-level expression of cloned genes. Journal of Molecular Biology, 189(1), 113–130.

    Blue/White Screening in Cloning
    • Purpose: To differentiate recombinant clones from non-recombinant colonies during cloning workflows.
    • How It Works: IPTG induces β-galactosidase expression; in the presence of X-gal, colonies with intact lacZα appear blue, while recombinant colonies with disrupted lacZ remain white.
    • Applications: Screening workflows using pUC19, pBluescript, and other multiple cloning site-containing vectors.

    Vieira, J., & Messing, J. (1982). The pUC plasmids, an M13mp7-derived system for insertion mutagenesis and sequencing with synthetic universal primers. Gene, 19(3), 259–268.

    Study of Gene Regulation and Promoter Function
    • Purpose: To investigate transcriptional regulation and promoter-controlled gene expression.
    • How It Works: IPTG induces reporter genes such as GFP or luciferase downstream of lac-based promoters, enabling quantitative analysis of promoter activity and regulatory dynamics.
    • Applications: Promoter mapping, transcriptional dynamics studies, functional genomics, and educational laboratory assays.

    Zaslaver, A., Bren, A., Ronen, M., Itzkovitz, S., Kikoin, I., Shavit, S., ... & Alon, U. (2006). A comprehensive library of fluorescent transcriptional reporters for Escherichia coli. Nature Methods, 3(8), 623–628.

    Metabolic Engineering and Pathway Control
    • Purpose: To enable temporal regulation of enzyme expression in engineered metabolic pathways.
    • How It Works: Genes encoding pathway enzymes are placed under lac-derived promoters, allowing controlled pathway activation and metabolic flux modulation through IPTG induction.
    • Applications: Production optimization for biofuels, amino acids, polymers, and specialty chemicals in engineered microbial systems.

    Zhang, F., Carothers, J. M., & Keasling, J. D. (2012). Design of a dynamic sensor-regulator system for production of chemicals and fuels derived from fatty acids. Nature Biotechnology, 30(4), 354–359.

    Conditional Gene Expression in Synthetic Biology
    • Purpose: To provide external control over synthetic gene circuits and regulatory networks.
    • How It Works: LacI-IPTG regulatory modules function as tunable switches, repressors, or oscillators within engineered biological systems.
    • Applications: Synthetic circuit design, biosensor development, microbial consortia regulation, and educational synthetic biology platforms.

    Elowitz, M. B., & Leibler, S. (2000). A synthetic oscillatory network of transcriptional regulators. Nature, 403(6767), 335–338.

     

    Reconstitution

    100mM IPTG stock solution

    1. Weigh 0.238 g of IPTG
    2. Add 10 mL sterile H2O. Dissolve completely.
    3. Prewet a 0.22 µm syringe filter by drawing through 5-10 mL of sterile H2O and discard water.
    4. Sterilize IPTG Stock through the prepared 0.22 µm syringe filter.
    5. Store in 1 mL aliquots at -20°C for up to 1 year.

     

    Storage/Handling

    Store powder IPTG desiccated at -20°C. Protect from light.
    For IPTG stock solution, store in 1 mL aliquots at -20°C for up to 1 year. IPTG is readily dissolved in sterile water.

     

    FAQ

    How does IPTG work?

    IPTG, which is similar to the lactose metabolite allolactose, induces the lac operon by binding to the lac repressor. Once IPTG binds to the lac repressor, a conformational change occurs, causing the lac repressor to dissociate from the lac promoter. Once the lac repressor dissociates, RNA polymerase binds to the promoter to initiate expression.

    How much IPTG should be used for expression/ What concentration of IPTG should be used for expression?

    Most papers recommend using between 0.1-1.0mM IPTG for expression. However, the amount you should use depends on your proteins. However, it is best to run an IPTG titration with ranges between 0.01-1.0mM and compare using SDS-PAGE to determine the optimal concentration. Something to keep in mind is higher concentrations of IPTG can cause inclusion bodies.

    Why should I use IPTG over lactose?

    IPTG is non-metabolizable, so its concentration remains stable and doesn’t get consumed by the bacteria.

    When should I add IPTG during culture growth?

    You should usually add IPTG at the mid-log phase (OD600 ≈ 0.4–0.6) to ensure cells are healthy and dividing rapidly.

    Do I need to autoclave IPTG?

    No—filter sterilize only. IPTG is heat-sensitive and should not be autoclaved.

    Does IPTG degrade over time?

    IPTG is stable when stored properly (aliquoted at -20°C, protected from light), but repeated freeze-thaw cycles should be avoided.

    Can IPTG be reused after thawing?

    The best practice is to use single-use aliquots of IPTG. Do not refreeze IPTG leftovers to avoid degradation or contamination.

    Can IPTG be toxic to cells?

    IPTG can be toxic at high concentrations or in sensitive strains. Lowering the IPTG concentration or using auto-induction media can help.


    IPTG Tutorial Videos


    Product Specifications

    Catalog ID: I2481
    Name(s): IPTG; Isopropyl-beta-D-thiogalactoside
    CAS #: 367-93-1
    Formula: C9H18O5S1
    MW: 238.30 g/mol
    Grade: MOLECULAR BIOLOGY GRADE
    Storage/handling: Store desiccated at -20°C. Protect from light.
    PubChem Chemical ID: 656894

    CITATIONS

    • 5 stars: 4 (100%)
    • 4 stars: 0 (0%)
    • 3 stars: 0 (0%)
    • 2 stars: 0 (0%)
    • 1 star: 0 (0%)
    A
    Anonymous
    How this item is used: For research.

    We only order IPTG from GoldBio because it's the best!

    A
    Anonymous
    How this item is used: We are using it to induce e. coli to express recombinent human protein.

    We have had excellent induction of our recombinently expressed protein using this product. This has been the most cost-effective induction product we have found.

    A
    Anonymous
    How this item is used: We study RNA-binding proteins and how they interact with RNA to regulate RNA processing. This involves a lot of protein expression.

    We love Goldbio's IPTG! Great price and has worked very well for us as we do a lot of protein expression. We would definitely recommend.

    A
    Anonymous

    Ordered again and will continue doing so!

    Featured Articles

    • combining antibiotics bacterial cell culture thumbnail

      Using Multiple Antibiotics in Bacterial Culture

      Antibiotics are important tools used to select for particular cell populations. For example, when bacteria are transformed with a plasmid, antibiotics are used to kill...

      Read more

    • How to make IPTG Stock Solution - Banner Image

      How to Make an IPTG Stock Solution

      IPTG is frequently used for blue/white colony screening and to induce protein expression in bacterial cultures. Fortunately, IPTG is very stable and easy to work...

      Read more

    • IPTG vs. Auto-Induction thumbnail image

      IPTG Induction vs Auto-Induction

      I had been optimizing my protein’s expression for months and I thought that I had already tried nearly everything that could be done. Still, I...

      Read more

    • IPTG optimization thumbnail - iptg tubes

      Optimizing Protein Expression with IPTG Induction

      Isopropyl b-D-1-thiogalactopyranoside (IPTG) induces recombinant protein expression in bacteria. But have you ever used your lab’s standard IPTG induction protocol and been disappointed with your...

      Read more

    • What Does the DE3 Represent in Competent Cells Like BL21(DE3) and DL39(DE3)?*

      What Does the DE3 Represent in Competent Cells Like BL21(DE3) and DL39(DE3)?*

      Expression systems are important tools in molecular biology, enabling researchers to produce proteins for research, diagnostics, and therapeutics. Examples of E. coli protein expression strains...

      Read more

    • Explain Alpha-Complementation and Blue-White Screening To Me Like I’m 10

      Explain Alpha-Complementation and Blue-White Screening To Me Like I’m 10

      Alpha-complementation – it’s a big phrase, but it’s not terribly hard to understand. The technical explanation of alpha-complementation involves combining two parts of a protein,...

      Read more

    • All About Differential Media in Gene Cloning - What it is and How it Works

      All About Differential Media in Gene Cloning - What it is and How it Works

      Differential media is culture media containing compounds that enable visual distinction between the microbes growing on it. These media leverage the distinct metabolic and biochemical...

      Read more

    Login

    Forgot your password?

    Don't have an account yet?
    Create account