The difference lies in the formulations of the forensicGEM and prepGEM kits and the extra QC and validation that goes into making the forensicGEM products. Because most forensicGEM DNA extraction will be used with multiplex STR analysis kits such as Identifiler and Profiler, the forensicGEM buffers have been modified for these sensitive reaction conditions. With the prepGEM™ range, most of the downstream applications are more robust and so we can use more powerful buffers and additives. ForensicGEM™ also undergoes more tests for the presence of human DNA before being released for sale.
The prepGEM/forensicGEM enzyme is very thermostable which means that it stores well at room temperature. However, for prolonged life we recommend that you keep it in the fridge, or for longer-term storage place it in a freezer at -20°C. This is mainly to safeguard against the solution being contaminated once opened.
At ZyGEM we have seen no loss of activity when the enzyme was cycled from -20°C to + 20°C each day for a month. However, if you have a large tube, and you are going to use it many times, it is wise to split it into smaller portions.
The DNA produced by prepGEM or forensicGEM is stable but given that the kits will be used on a range of substrates, a few commonsense safeguards should be taken for longer-term storage.
- Remove any residual tissue from the extract and transfer the DNA to a new tube. Be aware though that ZyGEM DNA is very high molecular weight and so centrifugation at high speeds will drop the DNA out of solution.
- Store at -20°C in a freezer.
- Buffer the DNA to 1x TE.
Because of the heat cycle DNA produced by ZyGEM kits is approximate 90% single-stranded and so fluorescence based methods using double-stranded specific dyes like PicoGEM (Invitrogen) will underestimate DNA yields. See our Application Note to advise on quantification.
For downstream PCR applications the yield and purity these methods generate is often unnecessary. One of the challenges of automating purification methods is the incidence of chemical carry-over into the eluted DNA. Whilst ZyGEM extraction methods do not yield pure DNA, the carry-over into the PCR assay is limited to cellular extracts and degraded proteins which rarely effect PCR.
Remember also, robots for DNA extraction by column or beads can do only that! ZyGEM allows you to use any liquid handling robot that can be used for other purposes.