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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/05/04 04:51:25」(JST)

Isopropyl β-D-1-thiogalactopyranoside (IPTG, also known as lad-y) 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.

IPTG, unlike allolactose, is not hydrolyzable by β-galactosidase. Therefore, its concentration remains constant during an experiment. For induction, a sterile, filtered 1 M solution of IPTG is typically added by 1:1000 dilution into a logarithmically growing bacterial culture, to give a final concentration of 1 mM. However, different concentrations of IPTG may also be used.

Mechanism of action

Like allolactose, IPTG binds to the lac repressor and releases the tetrameric repressor from the lac operator in an allosteric manner, thereby allowing the transcription of genes in the lac operon, such as the gene coding for beta-galactosidase, a hydrolase enzyme that catalyzes the hydrolysis of β-galactosides into monosaccharides. But unlike allolactose, the sulfur (S) atom creates a chemical bond which is non-hydrolyzable by the cell, preventing the cell from metabolizing or degrading the inducer. The concentration of IPTG therefore remains constant and the expression of lac p/o-controlled genes would not be inhibited during the experiment.^{[citation needed]}

IPTG uptake by E. coli can be independent of the action of lactose permease, since other transport pathways are also involved.^[1] At low concentration, IPTG enters cells through lactose permease, but at high concentrations (typically used for protein induction), IPTG can enter the cells independently of lactose permease.^[2]

Use in laboratory

IPTG is an effective inducer of protein expression in the concentration range of 100 μM to 1.0 mM. Concentration used depends on the strength of induction required, as well as the genotype of cells or plasmid used. If lacI^q, a mutant that over-produces the lac repressor, is present, then a higher concentration of IPTG may be necessary.^[3]

In blue-white screen, IPTG is used together with X-gal. Blue-white screen allows colonies that have been transformed with the recombinant plasmid rather than a non-recombinant one to be identified in cloning experiments.^{[citation needed]}

Other Names

Isopropyl 1-thio-b-D-galactopyranoside
Isopropyl 1-Thio-β-D-galactopyranoside
Isopropyl β-D-thiogalactopyranoside
Isopropyl-b-D-thiogalactopyranoside
Isopropyl-β-D-thiogalactopyranoside
1-(Isopropylthio)-β-Galactopyranside
D-β-isopropylthiogalactioside
Propan-2-yl 1-thio-β-D-galactopyranoside
β-D-Galactopyranoside, 1-methylethyl 1-thio-
(2S,4S,3R,5R,6R)-6-(hydroxymethyl)-2-(methylethylthio)-2H-3,4,5,6-tetrahydropyran-3,4,5-triol ^[4]

References

^ Hansen LH, Knudsen S, Sørensen SJ (June 1998). "The effect of the lacY gene on the induction of IPTG inducible promoters, studied in Escherichia coli and Pseudomonas fluorescens". Curr. Microbiol. 36 (6): 341–7. doi:10.1007/s002849900320. PMID 9608745.
^ Marbach A, Bettenbrock K. (2012). "lac operon induction in Escherichia coli: Systematic comparison of IPTG and TMG induction and influence of the transacetylase LacA". Journal of Biotechnology 157 (1): 82–8. doi:10.1016/j.jbiotec.2011.10.009. PMID 22079752.
^ BL21(DE3) Competent Cells, BL21 (DE3)pLysS Competent Cells, and BL21 Competent Cells Instruction Manual (Revision #066004e ed.). La Jolla, CA: Stratagene. 2006. p. 7.
^ http://www.chemspider.com/Chemical-Structure.571154.html

External links

IPTG's description on the Acros website
IPTG bound to proteins in the PDB

English Journal

Optimization of high cell density fermentation process for recombinant nitrilase production in E. coli.

Sohoni SV1, Nelapati D2, Sathe S2, Javadekar-Subhedar V3, Gaikaiwari RP3, Wangikar PP4.
Bioresource technology.Bioresour Technol.2015 Jul;188:202-8. doi: 10.1016/j.biortech.2015.02.038. Epub 2015 Feb 17.
Nitrilases constitute an important class of biocatalysts for chiral synthesis. This work was undertaken with the aim to optimize nitrilase production in a host that is well-studied for protein production. Process parameters were optimized for high cell density fermentation, in batch and fed-batch mo
PMID 25739996

Recombinant expression and purification of a MAP30-cell penetrating peptide fusion protein with higher anti-tumor bioactivity.

Lv Q1, Yang XZ2, Fu LY3, Lu YT3, Lu YH1, Zhao J4, Wang FJ5.
Protein expression and purification.Protein Expr Purif.2015 Jul;111:9-17. doi: 10.1016/j.pep.2015.03.008. Epub 2015 Mar 19.
MAP30 (Momordica Antiviral Protein 30 Kd), a single-stranded type-I ribosome inactivating protein, possesses versatile biological activities including anti-tumor abilities. However, the low efficiency penetrating into tumor cells hampers the tumoricidal effect of MAP30. This paper describes MAP30 fu
PMID 25797209

Efficient expression, purification and characterization of native human cystatin C in Escherichia coli periplasm.

Zhou Y1, Zhou Y2, Li J1, Chen J1, Yao Y1, Yu L1, Peng D3, Wang M3, Su D1, He Y4, Gou L5.
Protein expression and purification.Protein Expr Purif.2015 Jul;111:18-22. doi: 10.1016/j.pep.2015.03.006. Epub 2015 Mar 17.
Human cystatin C (HCC), encoded by cystatin 3 gene, is a 13.3kDa endogenous cysteine proteinase inhibitor and an important biomarker of renal function. However, expressing recombinant cystatin C is difficult because of low yield and inclusion bodies in Escherichia coli (E. coli). In this study, we c
PMID 25795130

Japanese Journal

High-throughput, high-level production of PS-tag-fused single-chain Fvs by microplate-based culture(BIOCHEMICAL ENGINEERING)

Kumada Yoichi,Takase Yuta,Sasaki Eiju [他],Kishimoto Michimasa
Journal of bioscience and bioengineering 111(5), 569-573, 2011-05-00
… Autoinduction System (OE system) was adopted to skip the laborious induction step of the addition of IPTG. … In a comparison of the productivity of flask cultures utilizing the 2YT-IPTG and OE systems, MBC utilizing the OE system was the highest, with approximately 1mg of insoluble scFv-PS obtained from each well under optimal conditions (1400rpm). …
NAID 110008661206

WSSV rVP26およびrVP28の大腸菌における発現条件とクルマエビにおける経口ワクチン最小有効投与量

佐藤純,金享〓,松井崇憲,西澤豊彦
魚病研究 45(4), 169-174, 2010-12-15
… 組換え大腸菌におけるrVPsの発現条件について検討した結果、rVP26およびrVP28は、何れも0.01mMのIPTGを添加して37℃で4時間培養した場合に発現量が最大となった。 … なお、0.01mM IPTG添加区でのrVPs収量は、1mM添加区の6倍以上であった。 …
NAID 10027671458

ダチョウ卵白由来グース型リゾチームとジスルフィド結合欠失変異体の大腸菌での発現系の確立

中嶋章悟,千々岩有紀,鳥潟隆雄,河村俊介
東海大学紀要. 農学部 29, 17-26, 2010-03-00
… IPTGで発現を誘導後、37℃で3時間培養した結果、OELは主に封入体として発現していた。 … しかしながら、IPTG添加後の培養を15℃で20時間行った結果、封入体を形成するOELの量が減少した。 …
NAID 120005106592

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リンク元	「isopropyl thiogalactoside」
関連記事	「IP」「IPT」

「isopropyl thiogalactoside」

Isopropyl β-D-1-thiogalactopyranoside
Identifiers
CAS Number	367-93-1
ChemSpider	571154
Jmol 3D model	Interactive image
MeSH	Isopropyl+Thiogalactoside
PubChem	656894
	InChI InChI=1S/C9H18O5S/c1-4(2)15-9-8(13)7(12)6(11)5(3-10)14-9/h4-13H,3H2,1-2H3/t5-,6+,7+,8-,9+/m1/s1 Key: BPHPUYQFMNQIOC-NXRLNHOXSA-N ; InChI=1/C9H18O5S/c1-4(2)15-9-8(13)7(12)6(11)5(3-10)14-9/h4-13H,3H2,1-2H3/t5-,6+,7+,8-,9+/m1/s1 Key: BPHPUYQFMNQIOC-NXRLNHOXBD ;
	SMILES CC(C)S[C@H]1[C@@H]([C@H]([C@H]([C@H](O1)CO)O)O)O ;
Properties
Chemical formula	C9H18O5S
Molar mass	238.30 g·mol−1
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
	Infobox references