A phage is a virus that parasitises bacteria; they have been a favourite lab device for years (get those bacteria!). However, the concept of using them as scaffolding for a combinatorial protein chemistry is relatively novel. Basically, it works like this:
- Clone the gene into the virus.
- Mutagenise the genes.
- Allow the bacteria to express the gene.
- Let the phage 'display' the protein on its coat.
- Select for the best phage.
- Extract gene and repeat.
The selection step depends on what the protein is for. Say it is a binding protein for sugar - then selection would be pouring the phage library through a sugar loaded column
. The ones that stick are the best and are given tiny, tiny cigars.