difference between precipipitating DNA with ethanol and isopropanol - (Sep/07/2007 )

I want to know, wat's the difference between precipitating DNA with ethanol and isopropanol?, For Ethanol precipitation in our lab we keep samples at -80, for 2-3 hrs(or -20 overnight) and for isopropanol precipitation simply at room temperature , 5-10 minutes. I want to know wat's the difference between two and which one is better?

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this has been discussed before.

Please have a look at these web pages :

differences iprOH / etOH :
http://www.protocol-online.org/forums/inde...?showtopic=5564
what makes precipitation :
http://www.protocol-online.org/forums/index.php?showtopic=28
topic on tips for ethanol purif :
http://www.protocol-online.org/forums/inde...?showtopic=5564

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so isoprapanol precipitate better than ethanol and ; ethanol evaporates quickly than isopropanol, so wat u suggest which of the 2 is better. Actually in our lab we use both for precipitation, n i was wondering if we can precipitate DNA within 5-10 min, by keeping it at room temp, then wat's the fun behind keeping it at-20, or -80, overnight or 2-3hrs during ethanol precipitation. If isopropanol method is more quick, without any compromise for yield, why it is less common practice than ethanol precipitation?

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well it dries more the pellet than ethanol. So in tough cases, it's harder to efficiently resuspend pellet. If you can't slight heat to help this step, isopropanol may be avoided. (for ex my sequencing reaction can't be heated. So i never use isopropanol).

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Well, the use of ethanol or isopropanol for precipitation of nucleic acids is mentioned in the Molecular Cloning: A Laboratory Manual (2nd edition).
Ethanol evaporate quickly than isopropanol, but more volumes of ethanol should be used than isopropanol. On the other hand, more salts may co-precipitated with nucleic acids using isopropanol, which may caused problem when redisolving the nucleic acids.
The temperature used for precipitation is primarily "thought" to be the lower the better, however, 4 oC is sufficient enough as mentioned in the Molecular Cloning: A Laboratory Manual.
Because the Molecular Cloning: A Laboratory Manual I reffered is a Chinese version, I can't tell you the page number.

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