What is the function of acetate solution in DNA extraction for PCR used - (Mar/07/2008 )

Hi, sorry for everyone because I am still a junior in this area (DNA extraction for PCR used). But I hope that I can understand the function of each chemical I will add into the process. May I know the function of adding acetate solution before we precipitate out DNA by using absolute ethanol ? What is the amount I need to add into the process ?

Kindly hope that someone can answer my simple question. Thanks for help

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Sodium acetate is used to help precipitate DNA. Search this forum for detailed discussion.

We use 1/10th volume of sodium acetate from 3M pH5.2 stock solution and 2 volumes of 100% DNA for precipitation.

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I see, Thanks for answering my question

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Scolix meant to say 100% ethanol there. Just a further question, is it the low pH or high salt that precipitates the DNA?

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If I am not mistaken, we can't have 100% EtOH. In fact, absolute EtOH is only 95%. Correct me if I am wrong.

By the way, that's the way to perform EtOH precipitation.

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pinko0528: Its 100% Ethanol , Sorry for the mistake.

killerkoz17: Thanks for covering me up.

virus_fan: We do have 95% ethanol and one which has higher alcohol concentration, could be close to 99% , but its called 100% ethanol.

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Pinko and Killer -- I believe the function of adding the acetate solution (either sodium acetate or ammonium acetate) is to raise the salt concentration, and therefore cause the nucleic acid to precipitate out of solution. ( I was told it's raising the salt the causes the pptn)
Ammonium acetate is supposed to be better for preventing precipitation of free nucleotides.

Virus -- As far as I know, you are correct about the etoh. Ethanol forms an azeotrope (?is that the right word? thinking back to general chem) when exposed to humidity in the air, and reaches equilibrium at 95%. I know though that some mol bio grade preparations of etoh are supplemented with methanol -- does the methanol prevent this?

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