IPTG is an analog of galactose that is non-metabolizable and inactivates the lac repressor to induce synthesis of β-galactosidase in E. coli. The expression of cloned genes under the control of the lac operon is induced by IPTG.It is also a substrate for thigalactosidetransacetylase and has been reported to induce penicillinase in bacteria.

IPTG is commonly used in cloning procedures that require induction of β-galactosidaseand is most often used with X-Gal (Gold Bio #X4281C) or Bluo-Gal (Gold Bio #B-673) for blue/white colony screening or Magenta-Gal (Gold Bio #B-378) for red/white colony screening of bacterial colonies.

IPTG is also used in the induction of recombinant proteins.In those systems, a protein of interest is encoded downstream of the IPTG inducible promoter.In the presence of IPTG, the protein of interest is induced in the cell culture.The culture can then be lysed and the protein expressed and purified through a number of methods, including His Tag or GST purification systems (for proteins with ligand tags).

GoldBio IPTG is made from a synthetic, non-animal origin.

Product Specifications:IPTGIsopropyl-beta-D-thiogalactoside

MOLECULAR BIOLOGY GRADE

Forumla: C₉H₁₈O₅S

MW: 238.30 g/mol

Purity: >99% by HPLC

Dioxane free

Storage/Handling: Store desiccated at -20°C. Protect from light.

PubChem Chemical ID:656894

IPTG Quick Answers:

How does IPTG induce the lac operon?

IPTG, which is similar to the lactose metabolite allolactose, induces the lac operon by binding to the lac repressor. Once IPTG binds to the lac repressor, a conformational change occurs, causing the lac repressor to dissociate from the lac promoter. Once the lac repressor dissociates, RNA polymerase binds to the promoter to initiate expression.

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How much IPTG should be used for expression/ What concentration of IPTG should be used for expression?

Most papers recommend using between 0.1mM – 1.0 mM IPTG for expression. However, the amount you should use depends on your proteins. However, it is best to run an IPTG titration with ranges between 0.01mM – 1.0mM and compare using SDS-PAGE to determine the optimal concentration. Something to keep in mind is higher concentrations of IPTG can cause inclusion bodies.

How do you dissolve IPTG?

IPTG can be dissolved in sterile water.

To make fresh 100mM IPTG stock solution:

• Weigh 0.238 g of IPTG
• Add 10 ml sterile H2O. Dissolve completely.
• Prewet a 0.22 µm syringe filter by drawing through 5-10 ml of sterile H2O and discard water.
• Sterilize IPTG Stock through the prepared 0.22 µm syringe filter.
• Store in 1 ml aliquots at -20°C for up to 1 year.

How do you store IPTG?

Store powder IPTG desiccated at -20°C. Protect from light. For IPTG stock solution, store in 1 ml aliquots at -20°C for up to 1 year.

What is IPTG used for?

Primary applications of IPTG include:

• Inducing proteins
• Blue-white screening using X-Gal

IPTG Tutorial Videos:

小鼠 1.       首先确定针的入口点。 2.       在膝关节的上部横跨腹部画一条想像的线。 3.       针应该沿着动物右侧这条线并贴近中间插入。（对于雌鼠，针的入口点位于最后一个乳头稍靠中间的部位。） 4.       针从小鼠的右侧插入避开盲肠，盲肠是腹部左侧一个大的充满液体的器官。小肠（位于右侧）不大可能被针刺穿。 5.       针的插入从插入点离尾部或横向太远如上显示将是危险的，可能会注射到后腿里，这样将会造成肌肉组织受伤。 6.       为完成腹腔注射，必须很好地控制好小鼠以防在操作过程中移动。一旦针插入到腹部避免器官受损伤。 7.       控制好小鼠并倾斜以便使其头向下，腹部露出来。 8.       用70%乙醇对注射位点进行彻底消毒。 9.       对于腹部注射我们建议用25-27 gauge直径的针，以30度角度插入腹部。 10.   针应插入大约半厘米（4-5mm）的深度。 11.   轻轻地吸出以确认针没有穿透血管，肠或膀胱。    a.       褐绿色吸出物表示针插进了小肠。    b.       黄色吸出物暗示针插进了膀胱。 12.   如果任何液体被吸出，表示您的溶液被污染了必须弃掉并用一个新的注射器和针头重新操作。 13.   如果没有液体被吸出，你可以开始注射。 14.   取出针头并记录下注射的时间，以确定信号达峰时间。 大鼠 按照小鼠腹腔注射操作流程。对于大鼠我们建议用一个25 gauge 直径的针头注射。 注意 l  确保针是倾斜的。 l  使动物的头倾斜向下为了使肠内物向下移动，以保持腹部四分区下部为空腔。 l  为了精确注射深度防止深层注射，我们建议放一根导管在针头上留出4-5mm为合适的深度。 l  确保注射体积，我们建议小鼠不超过2ml，大鼠不超过5ml（请参看附录关于不同动物和位点的不同注射体积。） l  给大鼠注射时，用布盖在大鼠的头部防止小鼠和研究人员紧张。 静脉注射