Isopropyl-β-d-thiogalactopyranoside (IPTG) is a kind of nonmetabolizable analog of lactose widely used for heterogeneous gene expression in Escherichia coli system. Lactose, a natural inducer of β-galactosidase gene, is the most popular substitute for IPTG due to its low cost and nontoxicity.

Application

Isopropyl β-d-1-thiogalactopyranoside 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.