PureLink™ Genomic DNA Mini Kit from Invitrogen

There are different ways of isolating genomic DNA from cultured cells, whole blood or solid tissues. Isolation of genomic DNA can be achieved by different precipitation methods as well as different approaches using membrane and column devices.

The PureLink™ Genomic DNA Mini Kit from Invitrogen, a silica membrane based isolation procedure, is equipped with sufficient material to process 10 samples. All the necessary buffers for lysis, proteinase K and RNase enzymes are included together with silica membrane spin columns and fitting collection tubes. The isolated DNA is 20 – 50 kb in size (according to the company). I found it very convenient that all the reagents included in the kit can be stored at room temperature. Therefore, there is no need for long searches in different storage compartments for all the things needed for isolation once you want to get started.

I use this kit on a regular basis for isolating genomic DNA from human cultured cell samples for different kinds of downstream applications including PCR. The kit is also utilized for the isolation of mitochondrial DNA from purified mammalian mitochondria.

One of the two major advantages of this kit is the inclusion of robust buffers which allow for cell disruption with proteinase K whithout the need for any mechanical lysis, and RNA elimination using the included RNase A. The second “plus” is the efficient binding of the DNA to the spin column silica membrane and rapid and easy clean up of the bound DNA.

The protocol for DNA isolation is quick and easy. One very important step to begin with is setting a heat block to 55ºC for the cell disruption. Ignoring this preparation step will result in major delay of DNA isolation. Depending on the sample that the DNA will be isolated from, there are different guidelines for cell or tissue disruption by proteinase K. A lot of times the volume of sample I was processing was greater than the capacity of the spin columns. In this case, you can perform very convenient multiple loading spins onto the same column. After two wash steps, the DNA gets eluted using the included elution buffer. One has the choice of eluting with 25 - 200 ul of buffer. This allows for flexibility regarding the suitable elution volume for different downstream applications as well as obtaining genomic DNA in the desired final concentration without the need for further dilution steps. Finally, another advantage is the possibility of performing a second elution step to recover even more DNA from the spin column. For me, this was especially important when performing mitochondrial DNA experiments with low starting material. Overall, the isolated DNA performed very well in downstream applications. Especially in PCR reactions there were no problems using the isolated DNA reagrding the primer performance and product specificity.

Altogether, I think this kit can be used in an easy and fast way, with some flexibility regarding the elution step.