0.1 volume of 3M sodium acetate (pH 5.2) are added to one volume of the aqueous solution. This gives a final concentration of 0.3 M sodium acetate6,7. 2 to 2.5 volumes of cold (–20℃C) absolute ethanol are added. The tube is left at –70℃C for one hour or at –20℃C for several hours (overnight). DNA is precipitated by centrifugation for 20 minutes at 4℃C (13000 rpm or 4000 g), the supernatant is discarded carefully, the remaining pellet washed with 300 µl of 80% ethanol to remove residual salt, centrifuged again for 5 minutes at 4℃C, the supernatant discarded again and the pellet dried in a vacuum evaporator (Speed Vac, Savant). The pellet is resuspended appropriately8. It can also be stored as a pellet stably at –20℃C [116, 117].
© 2001 Alexander Binder