RNA Pellet viscosity (Pectic acid?)

[Jørgen Borrebæk]

 I don't know about pectin, but I've read and heard that polysaccharides,
or even proteoglycans, might be a considerable contaminant in
RNA-islolations. 

When I isolate RNA from white blood cells (wich are rich in RNAses and
other substances like lipids, and relatively lean on the RNA side) I use
guanidine thiocyanate lysis, one acid phenol extraction and one
isopropanol precipitation.
This removes a lot of "goo".

After dissolving in water I go on with Dynal's oligo dT magnetic beads. 

I get some precipitation of this "substance X", but not too much to
interfere with the beads.

The mRNA exctracted should be perfect for RT-PCR, only I havn't tried it myself.

Jorgen


In article <37497E28.121B5704 at sph.unc.edu>, John Scott Meschke
<jmeschke at sph.unc.edu> wrote:

> List-
>     In my earlier message I was asking about two phases (aqueous and
> gelatinous)  produced from resuspension of RNA pellet after alcohol
> precipitation.  A friend has suggested that the problem could be pectin
> (or pectic acid).  The environmental sample that I was trying to recover
> spiked viral RNA from was a chloroform extract of tomato sauce.  Has
> anyone seen this problem before (with RNA extracts from plants,
> maybe?)?  Is the pectic acid theory sound?  What steps would I take to
> remove the pectic acid from the RNA or vice versa?  Any other ideas?
> Any help will be much appreciated.
> 
> Scott