Large Scale Extraction of Bacteria Plasmid DNA - (Jun/16/2007 )

Please tell me the usage of TE buffer, NaOH/SDS, potassium acetate , 70% alcohol, 95% alcohol and isopropanol

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First you lyse the cells with NaOH/SDS, so everything that is in the cell, will come out.
You neutralize this lysis buffer (too long the activity of this buffer will harm the plasmid DNA) with Kac, and a pellet of proteins and chromosomal DNA is formed (you need to get rid of this, so you will only pipet the supernatant).
In a solution of salts and 70% of ethanol, the plasmid DNA is precipitated, so the first time you add 95% ethanol to your solution in which the plasmid DNA is, in a volume that you get 70% of ethanol in the total volume.
Hereafter you wash this pellet with 70% ethanol, so the plasmid DNA will stay precipitated and you wash dirt away.
In TE buffer you dissolve the DNA pellet. It is a Tris-EDTA buffer. EDTA is an inhibitor of all kind of proteases and proteolytic enzymes, so it protects the DNA.

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