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"DsbC Set" is the supplement by adding to PUREfrex® series (Cell-free protein Synthesis Kits) for synthesizing proteins containing a disulfide bond in an active form.
Formation of a disulfide bond is an important process for folding and stability of secretory proteins such as enzymes or antibodies. A disulfide bond is usually formed by the oxidation of sulfhydryl group (SH-) of adjacent cysteine residues. Therefore, the formation efficiency of a disulfide bond depends on redox state. Additionally, disulfide bond isomerase which can catalyze the exchange of disulfide bridges may be also required for a correct pairing of cysteines.
DsbC Set is constituted of highly purified DsbC from E.coli known as disulfide bond isomerase, which can catalyze the disulfide bridge exchange, and GSSG (oxidized Glutathione) to make an oxidized environment.
General procedures for using PUREfrex® to synthesize functional proteins are shown in Figure.
Start by preparing the template DNA suitable to the protein synthesis with PUREfrex® and examine whether the protein of interest is synthesized. Redesign the nucleotide sequence of the template DNA if too little protein is synthesized.
Add DsbC Set as supplement to PUREfrex® reaction mixture if the solubility or activity of the synthesized protein is low.
This is a standard protocol for synthesizing proteins containing disulfide bonds.
Each solution of DsbC Set and PUREfrex®2.1 are mixed together in a same tube.
1. Thaw Solution I, Cysteine, GSH and GSSG by incubation at room temperature or 37 °C for 1 minute completely, and then cool on ice.
2. Thaw Solution II, III and DsbC on ice.
3. Mix each solution by vortex and centrifuge briefly to collect each solution at the bottom.
4. Assemble the reaction mixture in a tube as follows. Add the template DNA to 1 - 3 ng/µL per 1 kb.
|Solution I *1
|10 mM Cysteine
|80 mM GSH
|60 mM GSSG
|DsbC (80 μM) *2
|Template DNA *3
5. Incubate the tube at 37 °C for 2 - 6 hours with heat block or water bath.
Protein synthesis reaction is almost done until 6 hours, but some proteins require longer incubation (e.g. 24 hours) to form disulfide bonds between the correct pair of cysteine residues.
6. Analyze the synthesized products. Please add the same amount of H2O to the reaction for the sample of SDS-PAGE.
- This volume is different from Solution I of PUREfrex®2.0.
- DsbC is diluted with Dilution buffer included in DsbC Set.
- Please visit the template DNA preparation site.
Kit components <DsbC Set>
for 500 μL rxn
for 2 mL x 5 rxn
|100 µL x 5
|Oxidized glutathione (60 mM)
|100 µL x 5
|E.coli DsbC (320 µM *2) (No tags)
|-80 °C *3
|500 µL x 1
|30% glycerol buffer
- Indicated temperature shows storage temperature after opening the kit. Please store the kit at -80 °C before opening.
- It's same concentration as 7.5 mg/mL described in former instruction.
- The rest of solution should be frozen rapidly in liquid nitrogen or dry ice/ethanol, and be stored at -80 °C. Divide into aliquots, if necessary, and avoid refreeze and thaw as much as possible.
DsbC Set is developed for in vitro research only. DsbC Set should not be used for the therapy, diagnostic or administration to animals including human and should not be used as food or cosmetics etc. To avoid the contamination of nuclease, nuclease-free-treated water, reagents and materials should be used. We also recommend wearing gloves and mask.
"PUREfrex® is Registered in U.S. Patent and Trademark Office"
On the Resources page, you can find posters and technical notes about PUREfrex®.
Additionally, there are papers that use PUREfrex® or PURE system technology.
When your protein needs an assistance of molecular chaperone or a formation of a disulfide bond to form a correct conformation, we have supplemental reagents by simply adding to PUREfrex® series.
Cell-free Protein Synthesis Kits
Supplements – Chaperones –
These are supplement for PUREfrex® which is molecular chaperone to be aggregate-prone protein in a soluble form.
Supplements – Forming disulfide bonds –
This is supplement for synthesizing proteins containing disulfide bonds in an active form.