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Research Diagnostic Therapeutic

The Cherry™Express kit is an easy-to-use kit designed for visualizing your protein expression in E. coli

Direct Visualization of your protein of interest
Increase the solubility of your protein
Easy quantification of your protein of interest
Easy to follow purification steps
Rapid screening and optimization of protein expression
High yield of protein production using Staby™ systems

Name	Quantity	Reference	EUR
Cherry™Express T7 expression kit, electro-competent cells	5 RXNs	GE-CET7-05	360.00
Cherry™Express T7 expression kit, electro-competent cells	10 RXNs	GE-CET7-10	600.00
Cherry™Express T7 expression kit, chemically-competent cells	5 RXNs	GE-CET7-07	360.00
Cherry™Express T7 expression kit, chemically-competent cells	10 RXNs	GE-CET7-12	600.00

Delivery times

2 working days

Shipping conditions

Dry ice

Storage conditions

-80 °C

The CherryExpress™ T7 expression kit allows (i) cloning of your gene of interest into a stabilized plasmid and (ii) T7 expression of your protein of interest.

Each kit contains plasmid DNA, competent bacteria for cloning, competent bacteria for expression, regeneration medium, sequencing primers, expression control and the instruction manual.

Direct visualization of your recombinant protein

The Cherry™Express kit allows expression and direct visualization of your protein of interest during the whole process of protein production and purification without the need for any special requirements or reagents.

When using the Cherry™Express vector, your gene of interest is fused to a small sequence encoding a red polypeptide (heme binding part of cytochrome, 11 kDa) providing a visual aid for estimating expression level and solubility: bacteria expressing the fusion protein are red when the fused protein is soluble.

Easy quantification of the protein of interest

When using the Cherry™Express, it is possible to quantify the protein concentration at any step (from protein production to the end of purification process): a simple absorbance measurement at 413 nm allows specific and accurate calculation of the target protein concentration. Watch the video!!!

Easy-to-follow purification steps

The red color constitutes a visual marker throughout protein purification. Concentration of the fusion protein can be determined easily by spectral measurement at 413 nm (before and after purification). After purification, the tag can be cleaved using Enterokinase (a recognition site is inserted at the C-terminal end of the tag sequence).

Rapid screening and optimization of protein expression

The Cherry™Express system is convenient for rapid screening and optimization of protein solubility. You can visualize “on live” the expression of your protein under different conditions (temperature, time…). You just need to follow the OD at 413 nm! You don’t need to lyse cells and follow the purification process to know if your protein is expressed or not.

Increase the solubility of your protein!

As lack of solubility is a major problem when expressing recombinant protein in E. coli. When using the Cherry™Express vector, your gene of interest is fused to a small sequence encoding a red polypeptide (heme binding part of cytochrome, 11 kDa). This Cherry™ tag is highly soluble and thus, can increase the solubility of target proteins.

Leaflets

Cherry™ brochure

TDS

Cherry™Express manual

MSDS

Cherry™Express manual

Plasmid Sequence

FAQ

	Why does the StabyExpress™ T7 kit contain two kinds of electrocompetent bacteria?
	The StabyExpress™ kit contains CYS21 and SE1 electrocompetent bacteria. The CYS21 bacteria are used for cloning and the SE1 bacteria for expression. This enables to do the selection of the desired construction without expression of the gene of interest (no T7 RNA polymerase in the CYS21 bacteria).

	Why does the pStaby1 plasmid contain the ampicillin resistance gene although the StabyExpress™ T7 kit allows expression without antibiotics?
	It is better to use the ampicillin resistance of the plasmid during the electroporation step because the ccdB poison gene is not yet fully activated. Although the stabilization is fully effective after the DNA-electroporation step, ampicillin can be optionally used by the researcher to avoid contamination.

What is the advantage of the StabyExpress™ T7 kit if I do not find it a problem to use antibiotics (ampicillin or kanamycin) for plasmid stabilization?

It was shown previously that the efficiency of the plasmid stabilization using antibiotics depends on the protein expressed. The culture conditions must be adapted for each protein produced. Moreover, in intensive culture conditions (high biomass, high expression,…), the antibiotics are often not efficient due to antibiotic-inactivation (see Baneyx F. 1999; Corchero and Villaverde, 1998).
Consequently, using the StabyExpress™ kit, you get:
- better yield of expression
- better reproducibility and standardization (no need to adapt antibiotic resistance/quantity to each protein of interest).

	Why are the bacteria of the StabyExpress™ kit electrocompetent bacteria and not chemical competent bacteria?
	The transformation efficiency of electrocompetent bacteria is higher than the efficiency of chemical competent bacteria. This efficiency is particularly important during the cloning steps (electroporation in the CYS21 bacteria).

Is it dangerous to use the StabyExpress™ kit due to the poison and antidote genes or proteins?

Since the StabyExpress™ kit uses a natural bacterial poison (CcdB), one might fear that the poison could contaminate products extracted from the bacteria and could possibly be toxic for those using these products. However, all E. coli strains currently used in bacterial fermentation processes contain several poison-antidote operons in their chromosome. The CcdB poison is not toxic in mammalian cells. Finally, the poison and/or antidote proteins (CcdB and CcdA) are very small (8.7 and 11.7 kDa, respectively), and can therefore be easily removed from the protein extract during downstream purification (most proteins of interest have much higher molecular weights).

	I am already using a T7 expression system from another provider. Is it necessary to change the expression conditions with the StabyExpress™ T7 kit?
	The StabyExpress™ T7 kit is a new product combining a unique technology (plasmid stabilization with poison and antidote genes) with the very popular T7 expression system. The conditions for the cloning and expression steps are identical to a conventional T7 system.

What is the half-life of CcdA and CcdB in bacteria?
CcdB is very stable, more than 2 hours, whereas the half-life of CcdA is about 20 min.

How do you confirm a peptide is cyclised?

There are two types of cyclisations that can be performed:
1. N-terminal to C-terminal cyclisation
2. Disulfide bridge cyclisation
N-terminal to C-termal cyclisation is confirmed by a molecular weight shift of 18 mass units in the Maldi-Tof mass spectrum. A disulfide bridge cyclisation is confirmed by MS and HPLC before and after the cyclisation step. Although a mass shift of 2 mass units can be difficult to detect for certain peptides, an HPLC shift helps confirm the completion of the reaction.