112890 5-溴-4-氯-3-吲哚-β-D-吡喃半乳糖苷（X-β-Gal，X-Gal）

产品编号 产品名称 CAS号 产品包装

112890 5-溴-4-氯-3-吲哚-β-D-吡喃半乳糖苷（X-β-Gal，X-Gal） 7240-90-6 1g

023-15041 5-溴-4-氯-3-吲哚-β-D-吡喃半乳糖苷（X-β-Gal，X-Gal） 7240-90-6 100mg

029-15043 5-溴-4-氯-3-吲哚-β-D-吡喃半乳糖苷（X-β-Gal，X-Gal） 7240-90-6 1g

024-16791 5-溴-4-氯-3-吲哚-α-D-吡喃半乳糖苷（X-α-Gal） 107021-38-5 25mg

020-16793 5-溴-4-氯-3-吲哚-α-D-吡喃半乳糖苷（X-α-Gal） 107021-38-5 100mg

148941 Isopropyl-β-D(-)-thiogalactopyranoside（IPTG） 367-93-1 100mg

090-05141 Isopropyl-β-D(-)-thiogalactopyranoside（IPTG） 367-93-1 100mg

096-05143 Isopropyl-β-D(-)-thiogalactopyranoside（IPTG） 367-93-1 1g

094-05144 Isopropyl-β-D(-)-thiogalactopyranoside（IPTG） 367-93-1 10g

090-05146 Isopropyl-β-D(-)-thiogalactopyranoside（IPTG） 367-93-1 100g

025-15361 5-Bromo-4-chloro-3-indolyl-β-D-glucuronide Cyclohexylammonium Salt（X-Gluc） 114162-64-0 10mg

021-15363 5-Bromo-4-chloro-3-indolyl-β-D-glucuronide Cyclohexylammonium Salt （X-Gluc） 114162-64-0 100mg

一、X-Gal

X-Gal也称5-Bromo-4-chloro-3-indolyl β-D-galactopyranoside或5-Bromo-4-chloro-3-indolyl β-D-galactoside，中文名为5-溴-4-氯-3-吲哚-β-D-半乳糖苷。分子式为C14H15BrClNO6，分子量为408.63，CAS Number 7240-90-6，纯度>99%。进口分装。

本产品为白色至浅黄色粉末。

X-Gal是β-半乳糖苷酶(β-galactosidase)的显色底物，在β-半乳糖苷酶的催化下会产生蓝色产物。常用于β-半乳糖苷酶的原位染色检测以及蓝白斑筛选。

溶于DMSO，溶解度可达20mg/ml。也溶于DMF。

X-gal (also abbreviated BCIG for bromo-chloro-indolyl-galactopyranoside) is an organic compound consisting of galactose linked to a substituted indole. It is very heavily used in molecular biology.

Uses 

Cloning

In gene cloning, X-gal is used to indicate whether a cell expresses the β-galactosidase enzyme, which is encoded by the lacZ gene, in a technique called blue/white screening.

X-gal is cleaved by β-galactosidase yielding galactose and 5-bromo-4-chloro-3-hydroxyindole. The latter is then oxidized into 5,5'-dibromo-4,4'-dichloro-indigo, an insoluble blue product. Thus, if X-gal and an inducer of β-galactosidase (usually IPTG) is contained within an agar medium on a culture plate, colonies which have a functional lacZ gene can easily be distinguished.

When the technique of cloning plasmid vector genes within bacterial cells is optimal, X-gal is used to visually locate yeast or E. coli colonies that have been transformed by the desired plasmid vector in a blue-white screen. E. coli bacteria, which cannot produce the enzyme β-galactosidase (coded by lacZ gene of the lac operon), are transformed by absorbing the plasmid vectors, which contain an insert, in the lacZ open reading frame. After the transformation process, the bacteria is spread on nutrient agar plates, which mostly contain antibiotics as well. Most commercially available vectors contain an antibiotic-resistant gene. Successfully transformed bacteria has a truncated β-galactosidase gene, causing white colonies on the plate. Bacteria transformed by empty vectors, which do not contain an insert in the lacZ open reading frame, are now able to produce the enzyme β-galactosidase which can then cleave the X-gal present within the nutrient agar, resulting in a blue colony. Bacteria colonies that grow from bacteria that were not transformed do not contain this antibiotic-resistance, and thus, die. The plasmid vectors can also be coded to disrupt a different bacteria's ability to produce β-galactosidase, causing the desired bacteria colonies to grow to be white and non-transformed colonies to grow to be blue. This is the case with many commercially available cloning vectors, such as Promega's pGem-T Vectors, which carry lacZα, a truncated form of β-galactosidase, and require specific E. coli hosts a strain (such as DH5α) to achieve α-complementation.

Reporter

The lacZ gene may be used as a reporter in combination with growth media containing X-gal. In two-hybrid analysis for example, it is necessary to distinguish between those yeast or bacteria in which there is a successful interaction, leading to the binding of an activation domain to a promoter, and those in which there is not. If the promoter is linked to a lacZ gene, the production of β-galactosidase will be indicated by the production of blue pigment by colonies that host a successful interaction.[1] Due to its manual nature, this technique is limited to situations in which the number of colonies that must be distinguished is less than around 106.[1] The successful cleavage of X-gal also creates a noticeably foul odor due to the volatilization of indole.

Water testing

In addition to use in molecular biology, X-Gal is used to determine E. coli and coliform content in drinking water samples.

二、IPTG

中文品名: 异丙基-β-D-硫代吡喃半乳糖苷 

商品名称: Isopropyl β-D-1-Thiogalactopyranoside 

英文简称: IPTG 

产品别名: Isopropyl β-D-Thiogalactoside 

通用CAS : 367-93-1 

产品纯度: Sigma ≥99%, Merck ≥98% ，INALCO≥99% 

产品性状: 白色或白色粉末,溶于水后呈清亮无色液体 

分 子 式: C9H18O5S 

分 子 量: 238.30 

保存温度: 2-8°C冷藏保存 ,配制好后保存于-20°C，室温可放置一个月 

主要作用：异丙基硫代半乳糖苷(IPTG)是一种作用极强的诱导剂,不被细菌代谢而十分稳定,因此被实验室广泛应用 

IPTG是β–半乳糖苷酶的活性诱导物质。基于这个特性，当pUC系列的载体DNA（或其他带有lacZ 基因载体DNA）以lacZ 缺失细胞为宿主进行转化时、或用M13噬菌体的载体DNA进行转染时，如果在平板培养基中加入X–Gal和IPTG，由于β–半乳糖苷酶的α–互补性，可以根据是否呈现白色菌落（或噬菌斑）而方便地挑选出基因重组体。此外，它还可以作为具有lac或tac等启动子的表达载体的表达诱导物使用。

Isopropyl β-D-1-thiogalactopyranoside, abbreviated IPTG, is a molecular biology reagent.

This compound is used as a molecular mimic of allolactose, a lactose metabolite that triggers transcription of the lac operon. Unlike allolactose, the sulfur (S) atom creates a chemical bond which is non-hydrolyzable by the cell, preventing the cell from "eating up" or degrading the inductant; therefore the IPTG concentration remains constant. For induction, a sterile 1 M solution of IPTG is typically added by 1:1000 dilution into a logarithmically growing bacterial culture. Higher concentrations can be used.

IPTG induces the transcription of the gene coding for beta-galactosidase, a hydrolase enzyme that catalyzes the hydrolysis of β-galactosides into monosaccharides. One advantage of IPTG for in vivo studies is that since it cannot be metabolized by E. coli its concentration remains constant and the rate of expression of lac p/o-controlled genes, is not a variable in the experiment. IPTG intake is independent on the action of lactose permease, since other transport pathways are also involved.

In cloning experiments, colonies that have been transformed with the recombinant plasmid rather than a non-recombinant need to be identified. X-gal is a substance that can be metabolised by beta-galactosidase to produce a blue product. Thus cells expressing beta-galactosidase grown in the presence of X-gal and IPTG (to induce the expression) will turn blue. Where a DNA fragment has been inserted into the LacZ (one of the genes for beta-galactosidase) there will be no action upon X-gal and the cells will not turn blue, thus identifying the cells that carry recombinant plasmid rather than non-recombinant plasmid.

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.

三、X-α-Gal 

CAS:107021-38-5 

英明；5-Bromo-4-chloro-3-indoxyl-α-D-galactopyranoside;X-α-D-Galactoside 

分子式：C14H15BrCNO6 

分子量：408.64 g/mol 

报告基因Mel表达后，在含X-α-Gal的平板上显蓝色 

溶解性：清澈溶液（2%in DMF） 

储存：4℃ 避光避潮；长期存放-20℃ 

用途：X-α-半乳糖苷酶的作用底物，用于筛选含X-α-半乳糖苷酶基因的阳性酵母或细菌菌株。在组织化学中用于酶活性的检测。 

贮液： 

A)涂布于预制平板： 溶解24mg X-α-gal 于6 mL DMF中得到终浓度为4 mg/mL的溶液。 

B)直接加入琼脂中： 溶解60mg X-α-gal 于3 mL DMF中得到终浓度为20 mg/mL的溶液。 

参考用法： 

A)涂布于预制平板 

1.涂布200ul(15cm) 或者100ul（10cm） X-α-gal 贮液于预制平板上。 

2. 放于37 oC培养箱至液体被吸收（约4小时）。 

3. 将转化细菌或酵母涂于平板上并于合适温度培养至蓝色菌落出现。 

B)直接加入琼脂中 

1. 将已灭菌琼脂培养基冷却至55-50 oC。 

2. 在已冷却的培养基中加入20 mg/ ml X-α-Gal贮液，混匀，快速倒平板。

四、X-gluc

CAS：18656-96-7 

分子式：C14H13BrClNO7.C6H13N 

分子量：521.8 

外观：白色粉末 

溶解性：清澈溶液（2％in DMF） 

用途： 

检测大肠杆菌中uidA基因（β-葡萄糖苷酶基因β-glucuronidase, GUS）的底物。95%的大肠杆菌具有β-葡萄糖苷酶基因，用这种发色底物的培养基可以检测以及定量食品样本如肉、奶制品以及贝类中的大肠杆菌数量，以及在临床上检测尿路感染。国际上普遍采用该产品取代传统方法以精确检测饮用水中的大肠杆菌数量，该方法大大降低了假阳性和假阴性。该产品也用于快速检测植物中GUS基因融合标记。 

β-葡糖醛酸酶（β-glucuronidase (GUS)）基因检测的显色底物。