un691cs at genius.embnet.dkfz-heidelberg
Tue Apr 28 05:29:24 EST 1998
On 28 Apr 1998 01:21:53 -0700, methods at 163.NET said:
>I read on MOLECULAR CLONING that ethanol can't be use to precipated large
>MW plasmid when try to eliminate the minimum amount of chloroform after ph
>enol extraction. So could anybody kindly tell me why? I think it is to avoi
>d the damage of the nucleic acid molecule, but is there the absolute inhib
>ition on its use?
it is generally not so good to precipitate large DNAs (>10kb), as the DNA may get
nicks AND is difficult to dissolve afterwards.
However, I have precipiated plasmids of 25kb and lambda phage DNA of >50kb,
and it does seem to work.
some hints to protect your DNA:
- do not vortex, but treat gently
- do not pipet the DNA to get it into solution, instead leave it at
- do not freeze the DNA, store it at 4C
- do not use a speedvac: dry the pellet to air for as short a time
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