IPTG (Isopropyl ß-D-1-thiogalactopyranoside), is a molecular biology reagent. It is used in conjunction with X-Gal or Bluo-Gal in blue-white selection of recombinant bacterial colonies that induce expression of the lac operon in Escherichia coli. This compound is a molecular mimic of allolactose, a lactose metabolite that triggers transcription of the lac operon and it is therefore used to induce protein expression where the gene is under the control of the lac operator. It has been used for the expression of recombinant genes in E. coli.
Synonym: IPTG, Isopropyl β-D-1-thiogalactopyranoside, Isopropyl β-D-thiogalactoside, iptg
CAS Number: 367-93-1
Empirical Formula (Hill Notation): C9H18O5S
Molecular Weight: 238.30
Beilstein Registry Number: 4631
MDL number: MFCD00063273
PubChem Substance ID: 329815691
Working concentration: Final concentration should be 0.2 mM.
Storage conditions (working solution): Stock solutions of the product in water (e.g., 1 M IPTG) stored at -15 to -25 °C, are stable up to six months.
Isopropyl-ß-D-thiogalactopyranoside (IPTG) is a chemical analogue of galactose, which cannot be hydrolyzed by the enzyme ß–Galactosidase. Hence, it induces the E. coli lac operon activity by binding and inhibiting the lac repressor without being degraded. Genes controlled by the lac or tac promotor/operator sequences are expressed to high levels in the presence of IPTG.
Blue/white color screening
Induction of lac operon for protein expression
Genes controlled by the lac or tac promotor/operator sequences are expressed to high levels in the presence of IPTG
>99% by HPLC, Dioxane free