Precipitation occurs when adjacent DNA helices are affected simultaneously ... we use a 50% isopropanol solution with 300 mM NaCl, 10 mM MgCl 2 and 25 mM EDTA to remove spermidine.

Transfer the entire solution to the nebulizer ... and 'McrBC-treated' DNA samples by precipitation with 3 volumes of ethanol in the presence of 100 mM NaCl (add 2 μl of 5 M NaCl).