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Isopropyl β-d-1-thiogalactopyranoside (IPTG) is a molecular biology reagent. 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 .
Isopropyl-β-D-thiogalactopyranoside (IPTG) is frequently used as an inducer of the lac operon for physiological work. IPTG binds to repressor and inactivates it, but is not a substrate for β-galactosidase. One advantage of IPTG for in vivo studies is that since it cannot be metabolized by E. coli.
Often, the plate containing X-Gal also contains IPTG (isopropyl β-D-1-thiogalactopyranoside). IPTG is a chemical structure analogue of lactose. [7] However, IPTG cannot be hydrolyzed by β-galactosidase. IPTG is used as an inducer that binds to lac repressor releasing the DNA and allowing transcription.
While E. coli BL21(DE3) supports the expression of genes under the control of constitutive promoters, it is specifically engineered for IPTG induction of recombinant genes under the control of a T7 promoter. The realized induction strength depends on several factors, including the IPTG concentration and the timing of its supplementation. [5]
Isopropyl β-D-1-thiogalactopyranoside (IPTG), which functions as the inducer of the lac operon, may be used in the media to enhance the expression of LacZ. X-gal is an expensive material, thus other methods have been developed in order to screen bacteria. GFP has been developed as an alternative to help screen bacteria.
IPTG is a reagent which mimics the structure of allolactose, and can therefore bind to the lac repressor and prevent it from inhibiting gene expression. Once enough IPTG is added, the T7 gene is normally transcribed and so transcription of the gene of interest downstream of the T7 promoter also begins. [ 6 ]
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Once the cells reach a certain point in their growth, isopropyl β-D-1-thiogalactopyranoside (IPTG) is added. IPTG, a molecule similar to lactose, but with a sulfur bond that is not hydrolyzable so that E. coli does not digest it, is used to activate or "induce" the production of the new protein. Once the cells are induced, it is difficult to ...