PureLink™ Gel Extraction Kit From Invitrogen

Often in molecular biology, it is necessary to recover DNA that has been run on an agarose gels. It is now common for researchers to buy kits to streamline this operation. The PureLink™ Gel Extraction Kit from Invitrogen is one such product.

The PureLink™ Gel Extraction Kit from Invitrogen uses column based silica membranes to capture DNA from solubilized gel slices. DNA can be extracted from both high and low melting point gels with only minor changes in protocol, and both TAE and TBE buffers are supported. Columns can capture up to 15 µg DNA, provided the size of the fragment is 40 bp to 10 kb. According to the kit instructions, DNA recovery is better than 80% and the whole procedure takes less than 30 minutes. It is important to note that this kit is not recommended for extracting super coiled plasmid or genomic DNA. In addition, the kit cannot be used to extract DNA from PCR reactions as similar products from other companies are able to do.

The protocol is similar to other gel extraction kits. After electrophoresis is performed, the linear DNA is excised from the gel using a clean scalpel, taking care to minimize the excess agarose surrounding the DNA. The slice is then weighed so the correct amount of Solubilization Buffer can be added (30 µl per 10 mg gel). The gel slice and correct amount of Buffer are then incubated at 50C for 15 minutes to dissolve the gel slice, plus an extra 5 minutes to complete solubilization. The next step is to bind the DNA to the silica membrane in the column, which can be done by centrifugation or using a vacuum manifold (which may be preferable for high throughput users). Briefly, the DNA is pulled through the column and bound onto the membranes. The DNA is then washed twice, before the DNA is eluted with warmed TE buffer.

We have been using the PureLink™ Gel Extraction Kit from Invitrogen for several months in our laboratory and have found it to be easy to use, and consistently give high yields of DNA. The purified product is normally used for a variety of procedures such as restriction digests, ligations and sequencing with no difficulties. We normally approximate the weight of the gel to remove the fiddly weighing step, which makes the procedure faster. While kits that allow both gel extraction and PCR purification are useful, we have found the quality of the separate Invitrogen kits makes up for the lack of flexibility.