purification of radioactive probe

[Kay Schink]

Simone Marker schrieb:
> Hi,
> 
> does anyone know if it is really necessary to purify a radioactive DNA probe 
> after labelling it by random priming? I want to use it on a northern blot. 
> So far, I worked with DIG-labelled probes, that do not need to be purified 
> after labelling. They are used directly in the hybridisation solution. Is it 
> different with radioactive probes? Do you think that precipitation by salt 
> and alcohol is sufficient for purification?
> 
> Thank you very much,
> Simone 
> 
> 


Hi Simone!

We purify our radioactive probes using small gel filtration spin columns 
(I think it's called MobiSpin) - you get rid of most unincooperated 
radioactivity, which is retained in the column, while your labelled 
probe is in the flow-through. It makes it much nicer to work with the 
probe because it is not as radiactive as the whole reaction mixture..

Good luck

  Kay