Q: Best method for precipitation of small RNA's ( 10-20nt ) ?

[Claus Stefan Voertler]

Hi Gerd,

you are really trying to push to the limit here...:-) 
Our experience in the lab is that anything bigger than  15-20nt will 
precipitate under the normal conditions (1/10vol 3M NaAc, 2.5vol  
EtOH) Increasing the conc of NaAc may helped in some cases (to 
1/3vol). 2-3M NH4Ac works equally well. A coprecipitant is optional 
(glycogen or bulk tRNA) but you have anyway a lot of other nucleic 
acids arround. So there are good chances of precipitating a 10 to 
15mer with these conditions - might just not be quantitative.

In any case: Why not loading the material directly onto the dPAGE-gel? 
If you need to precipitate in order to concentrate the sample, you 
could also use ultrafiltration. This works also fine to remove 
salts/buffer-components interfering with the electrophoresis...

Stefan

_________________________________________________________

Claus Stefan Vörtler       MPI für experimentelle Medizin
                           Hermann-Rein-Str.3
                           D-37077 Göttingen
                           Germany
_________________________________________________________

User wrote:
> 
> Hi there !
> 
> I'm doing transcription reactions with nuclear extracts. I'm searching for
> very short transcripts. So what is the best method to ensure precipitation of
> this trasnscripts and analyse them by PAGE after that ?
> 
> Gerd Emde
> 


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