- Blue/white colony screening
- Expression of cloned genes that are under control of the lac promoter
IPTG (isopropyl-beta-D-thiogalactopyranoside) is a highly stable synthetic analogue of lactose. It inactivates the lac repressor and induces synthesis of beta-galactosidase, an enzyme that
promotes lactose utilization. The IPTG is used to induce the expression of cloned genes which are under control of the lac operon. It is used in conjunction with X-Gal to determine the lac
phenotype in blue/white colony screening.
- Greater than 99.8 % purity confirmed by HPLC
- Functionally tested in blue/white colony screening
Preparation of stock solution:
Dissolve IPTG in water to a final concentration of 200 mg/ml. Sterilize solution using a 0.2 μm filter, dispense in aliquots, and store at –20°C. The sterilized solution is usually stable for
several months when stored at –20°C.
IPTG should be used at a final concentration of 250–350 μg/ml in culture plates, top agar, or liquid culture. Alternatively, an appropriate amount of IPTG can be spread onto the surface of an
agar plate and allowed to dry before inoculating with bacterial culture.