help with DNA extraction

bev at bev at
Mon Aug 12 20:11:55 EST 2002

Dr. Klaus Eimert wrote:

> Hi,

> are you working with plants? In plants, the viscosity you mention is 
> often a result of large amounts of polysaccharides co-precipitating with 
> the DNA. We struggeled with that problem, too. In our hands, high 
> salinity during ethanol precipitation worked very well, regardless of 
> what kind of buffers or isolation protocol we used. It has been described 
> in Lohdi et al. 1994, Plant Mol Biol 12:6-13.
> In short: use your favorite protocol for isolation and, before ethanol 
> precipitation, add 0.5 volumes of 5 M NaCl. Then add two volumes of 96% 
> ethanol and precipitate as usual. Since the solubility of the 
> polysaccharides (most of them, anyway) is now much higher, they won't co-
> precipitate. Wash twice to get rid of the salt and resuspend in TE. 
> It's worth a try, I think.
> Hope that helps,

> Klaus

Hi Klaus,

I am actually working with human tissue, fresh kidney or prostate, so I don't
think my problem is polysaccharides. I have heard of that being a problem in 
plant and fungal extractions. However, I will still give the 0.5 volumes of 5M NaCl
a try just in case it helps. Thanks for your response,

Bev Shannon,
Tissugen Pty Ltd,
Perth, Western Australia

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