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Role of Sodium Acetate in DNA precipitation - (Oct/18/2005 )

Hi everyone,

I would like to know what is/are the functions of sodium acetate in DNA precipitation? Why is the pH5.2? I have experience precipitating DNA after phenol:chloroform:IAA (25:24:1) extraction using 3M sodium acetate pH5.2. As soon as I add colded 95% ethanol after sodium acetate (1/10 volume) for DNA precipitation, the whole solution turned cloudy with a lot of white precipitate, precipitating down. Is it the salt or what?

Thanks for all the replies in advance, really appreciate your replies.



acetate is negatively charged
low pH contibutes to charge positively the DNA
combination of this plus high salt molarity enhances formation of aggregates of DNA and facilitates the pelleting procedure.


Thanks a lot fred 33, for you really quick reply. Awesome.


Sodium acetate does not crystallize but inhibits the Klenow fragment