4.9.3. Magnesium concentration
Magnesium is an essential ion required for most nucleic-acid processing enzymes, particularly polymerases. The use of ion-chelating agents, such as EDTA, to stop or inhibit polymerases and nucleases attests to the importance of Mg+2 in nucleic acid reactions (Green and Sambrook, 2012). Most commercial buffers contain optimized concentrations of Mg+2, so that currently there is little need for further Mg+2 optimization. Above a certain minimum concentration, magnesium has only marginal influence on reaction efficiency and almost none on reaction specificity.