K

There's a slight problem at the lab at the moment. We aren't getting any DNA. The lovely little DNA extraction protocol is not actually extracting huge amounts of DNA for us, if fact it seems to be producing pretty much no DNA for us.

We've checked through the troubleshooting, and in various technique manuals, and found a couple of modifying features to add to our protocol, which will hopefully make it more productive. Most of them are fairly basic (longer incubation's etc.) but the one that caught my eye was the addition of proteinase K at the denaturing step. When you add SDS (which breaks down all the phage proteins to supposedly release the DNA) you also add this mystery stuff called proteinase K.

Not wanting something so scientific to be shooting over my Magical Event Horizon, I went to take a look at what it was. A protease is a substance that breaks down proteins, and it turns out that this is exactly what proteinase K does, it is far more active when surrounded by SDS as well, so hopefully the combination of the two will pretty much shred all the phage proteins releasing all the DNA (as I said, phages are nothing but DNA and protein).

One interesting thing I did find though is that proteinase K was extracted from a fungus (called Tritirachium album Limber). It's fairly deadly as well, it can pull apart all sorts of different proteins. It makes sense for a fungi to possess a powerful proteinase like this as fungi are saprotrophic feeders; they release the enzymes to digest their food outside of their actual bodies and then just absorb all the nutrients left behind.

I thought that the name 'proteinase K' might turn out to have a fairly interesting backstory (why K?) but it is, in fact, spectacularly boring. It was named Protienase K due to its keratin hydrolyzing activity which, seeing as it hydrolyses (breaks down) a large number of proteins seems fairly arbitrary. Biologists have very little imagination sometimes.

If you have a desperate longing to get hold of some proteinase K you can buy it here.
It is fairly expensive though; £39.00 for 2ml.