The QuickStep™ 2 PCR Purification Kit from Edge BioSystems (Gaithersburg, MD) is designed to separate double-stranded DNA products away from primers and other single-stranded DNA, as well as salts, dNTPs, and proteins. The kit consists of their proprietary resin (
Solid-phase
Oligo/
Protein
Eliminator; SOPE™2) and gel filtration spin columns. In most kit-based purification and clean-up systems, the desired DNA product is immobilized, either by binding to a resin or precipitation, while contaminants are removed. The purified DNA must then be eluted from the resin, or the precipitated DNA resuspended in water or buffer. The QuickStep™ system, on the other hand, works in reverse by binding up the contaminants while the desired DNA passes through the gel filtration column. One of the advantages of this approach is speed. The whole procedure takes less than 10 minutes.
I recently used the QuickStep™ 2 Kit to clean-up a PCR reaction. The protocol is extremely easy and consists of adding one-fifth volume of the SOPE™2 resin to the PCR reaction (e.g. 10 ul resin for a 50 ul reaction), mixing well, and letting it sit on the bench while the gel filtration column is centrifuged for 3 min to get rid of the hydration solution (water). The PCR reaction/resin mixture is then pipetted onto the gel filtration matrix and the column spun for 2 min at 750 x g. The purified DNA is in the eluate.
Since this was my first time using the product, I ran a gel of some of the purified amplicon and compared it to unpurified amplicon from the same reaction. I also compared the QuickStep™ 2 method to a precipitation-based clean-up kit.
In the figure, lane 1 is unpurified amplicon, lane 2 is QuickStep™ 2 purified, lane 3 is a precipitation plus co-precipitant purification, and lane 4 is the same as lane 3 except with no co-precipitant. Based on the stained gel, all purification methods performed very well, exhibiting excellent recovery and removal of primers. Although recovery was high in all cases, the best was with the precipitation plus co-precipitant. The QuickStep™ 2 Kit performed approximately equivalently to the precipitation without co-precipitant but took considerably less time (less than 10 min vs. ~40 min).
In addition to the outstanding performance of the QuickStep™ 2 PCR Purification Kit, Edge BioSystems offers a variety of packaging options. Kits are available for 36 or 108 individual samples, and in plate format for 96- and 384-well plates. The SOPE™ resin and gel filtration cartridges can also be purchased separately.
Michael Campa, PhD
Assoc. Research Professor
Duke University Medical Center
Radiology