Quantitative DNA slot blot analysis: inhibition of DNA binding to membranes by magnesium ions.

Titers of wild-type and recombinant adeno-associated viruses are routinely determined by DNA slot blot analysis. The binding of viral DNA to nylon membranes was found to be inhibited by magnesium ions, which are critical components of the DNase I digestion carried out prior to slot blot analysis. Mg2+ions also interfered with the adsorption of plasmid DNA to nylon and nitrocellulose membranes. These observations yield practical insights into the poorly understood mechanisms by which DNA molecules are retained on solid supports.