IPTG

From Freepedia

Common abbreviation for Isopropyl β-D-1-thiogalactopyranoside, a molecular biology reagent. Molecular weight = 238.3.

This compound is used as a molecular mimic of allolactose, a lactose metabolite that triggers transcription of the lac operon. Many regulatory elements of the lac operon are used in inducible recombinant protein systems; IPTG is an effective inducer in the concentration range of 100 μM to 1.5 mM.