ExiProgen™ EC-Disulfide Protein Synthesis Kit (8 reactions)
ExiProgen™ EC-Disulfide Protein Synthesis Kit (8 reactions)
ExiProgen™ EC-Disulfide Protein Synthesis Kit allows automatic synthesis of proteins with disulfide bonds capable of acquiring maximum of 8 types in a single reaction. As proteins with 9 disulfide bonds can be easily synthesized, it is much more efficient to use then protein expression using cells. After mounting the kit including the template DNA to the ExiProgen™, by operating the Protocol No. 905, all the reactions from the expression, purification, and dialysis are fully automated, with the final target proteins recovered dissolved in the storage buffer.
-20℃ (E. coli extract recommended at -70℃ or less)
*E. coli extract
8-strip tube (Yellow) x 1 ea
8-strip tube (Violet) x 1 ea
8-strip tube (White) x 1 ea
35 ml x 2 bottle
Positive control DNA
1.5 ml tube x 1 ea
*E. coli extract (8 strip tube): As T7 RNA polymerase and ribosome are included, it is recommended to be stored at temperatures below -70 ℃ immediately upon the receive. Performance will decrease upon repeated freezing and thawing.
The protein expression is done through SECF protein expression method developed from our company in an oxidizing environment and be purified using Ni-NTA magnetic beads.
The kit also contain a chaperone protein for helping the protein folding optimized for the buffer composition to synthesize proteins with disulfide bonds.
Mix the template DNA and the E. coli extract with the Master Mixture in the kit inside the reaction tube.
Then insert the reaction tube into the ExiProgen™ reaction block and install the remaining kit to start the instrument.
Note) It is recommended to use plasmid DNA over PCR products as there was no significant increase when the latter was chosen over ExiProgen™ EC Protein Synthesis Kit.
▶ Experimental Results
1. This kit is capable of synthesizing proteins with disulfide bonds and their activities are tested.
Figure 1.Left Pannel : Expression and purification of ScFV and rtPA.
- M: AccuLadder™ Protein Size Marker (Low) - 1: ScFv (it has 2 disulfide bonds.) - 2: rtPA (it has 9 disulfide bonds) * Amount of purification sample is 1/40 of total sample.
Right panel: rtPA synthesized with ExiProgen™ EC-Disulfide Protein Synthesis Kit has an enzyme activity.
- 1: Synthesis sample using ExiProgen™ EC-Maxi Protein Synthesis kit. - 2: Synthesis sample using ExiProgen™ EC-Disulfide Protein Synthesis kit. * rtPA activity was measured by incubating with chromogenic substrate S-2288.
Currently, the molecular weights (MW) of synthesizable proteins ranging from 10 kDa ~150 kDA were tested and validated. Though it is theoretically possible, it is not recommended to go over or under that scale.
Figure 1. SDS-PAGE data of various proteins synthesized from various templates M: AccuRapid™ Protein Size Marker (Broad) (Cat. No. D-2010, Bioneer) 1: CalmL3 (17.5 kDa) 2: DUSP3 (22 kDa) 3: CAT (24 kDa) 4: AcGFP (29 kDa) 5: ERFP (31 kDa) 6: EF-Ts (34 kDa) 7: VF (45 kDa) 8: BM3 (117 kDa)
The time it takes to obtain the proteins depends on the synthesized kit. For ExiProgen™ EC Protein synthesis Kit, it takes 6 hours for the expression to be completed. Refer to the table for more information on other kits. Additionally, after the final purification step, ExiProgen™ stores the target proteins in low temperature from 4°C to 8°C inside the reaction block. Even when the device is operated overnight, those can be also stably kept without separate refrigeration devices.
* It is recommended to use the Manual Kit for simpler controlling of expression volumes if only small scales of protein synthesis are required.
The template DNA should have the structure of T7 promoter, RBS, His-tag and T7 terminator as shown below. Depending on where the His-tag is attached, you can choose between two different types of expression, folding, and separation purification. At this time, the template type can be either plasmid DNA or PCR product. When preparing with a PCR product, it is advantageous to prepare several types of templates quickly, but the yield of protein synthesis may be slightly lower than that of plasmid DNA. Especially, when using SECF method for long time reaction for large-scale expression, the stability of template is important, so we recommend plasmid template.
1) When plasmid DNA is used as a template, It is recommended to use pBIVT vector (Cat. No. K-7350, Bioneer) which is exclusive to in vitro translation, but T7 system, RBS, and His-tag for purification can also be used. Using the AccuPrep® Nano-Plus Plasmid Mini Extraction Kit (Cat. No. K-3112, Bioneer), cloned plasmid DNA can be isolated with high-yield, high-purity only within 10 minutes
2) When using a PCR product as a template, ExiProgen™ ProXpress PCR Template Kit (Cat. No. K-7400, Bioneer) can be used for amplification of the target gene for preparing large quantities of the templates by PCR without the cloning step. For the best results, the purity of the acquired template DNA should be in the range of A260 / 280 ratio of 1.8 - 2.0.
As the quantity of template DNA used effects the efficiency of protein synthesis, it is very important to use its appropriate amount. Since the number of copies is important for the template used, it should be quantitatively proportional to the size of DNA. Generally, for a plasmid DNA, 1.34 ug/ml is used per 1 kb while for DNA fragments in PCR products, 670 ng/ml is used per 1 kb. Please refer to the answer from Question 2 for more details.
e.g.) ExiProgen™ EC Protein Synthesis Kit (Cat. No. K-7300, Bioneer) uses 0.75 ml during protein expression. Thus, concentration of 5 μg / reaction is required for 5 kb of plasmid DNA.
For the optimal synthesis, we recommend screening for protein expression levels by template DNA concentrations.
Since the protein synthesis kit uses E. coli bacterial expression system, if the templates are optimized for E. coli codons, the protein expression levels and the success rates can be increased.
The purification methods used in ExiProgen™ utilize average diameter or 400 nm Silica Magnetic Nanobeads developed with Bioneer’s proprietary technology. On the surface of the beads, Ni-NTA is firmly immobilized, allowing purification of proteins by affinity purification methods through the strong binding of His-tag of the target proteins. These processes are fully automatic in ExiProgen™.
Due to the tertiary structure of the final product of proteins, if the His-tag at the N- or C-terminal is not exposed, to the surface, Ni-NTA can’t recognize it, lowering the purification efficiency. Thus, it is important to identify the protein structure and undergo a thorough check when designing the template DNA. If the protein structure is not known, it is advised test the expression and purification efficiency both templates with His-tag attached on N- or C- terminal. If those cannot be performed at both ends, it is recommended to increase the number of His-tag histidine to enhance them. If this method also does not work, then try attaching another protein which helps the protein expression to the N-terminal to produce a soluble fusion protein.
We are continuing to develop an efficient expression system, so please contact us if the protein expression fails.
Most of the time, this is caused by poor protein expression. It is recommended to use a manual kit AccuRapid™ to find the optimal protein expression condition on a small scale. Try running the same condition in ExiProgen™ for improved efficiency. If the expression level is high but the purification level is low, try changing the position of His-tag as explained in Question 7.
Each ExiProgen™ protein synthesis kit is consisted of two boxes: Kit ① and Kit ②.
It is highly recommended to store the purification kit (Kit ①) at 4℃ ~ 8℃ and Expression Kit (Kit ②) at -20℃ ~ -70℃. For the long-term storage, it is adviced to keep the E. coli extract included the Expression Kit (Kit ②) at -70℃.
For more details, please refer to the box and the user manual.
The cartridges is designed to be used up to 4 times. However, it is not recommended to use them overnight if you want to do so.
Store the them at the recommended temperature immediately after the ExiProgen™ operation. Conceal with cartridge covers and store cartridge ① at 4℃ to 8℃ and cartridge ② to -20 ° to -70 ° C.
The performance of the E. coli extract will be decreased on the occasion of repeated freezing and thawing. As it is packaged in a single tube for one-time use, please make sure to check the kit components and use it according to your experimental plans.