Magnesium choride is used in PCR and as a growth medium component for some formulations.
Magnesium chloride comes in two common forms:
- anhydrous 95.211 g/mol
- hexahydrate 203.31 g/mol
Magnesium chloride has a solubility of 529 g/L at 0 °C. This makes about 5M the highest practical stock solution concentration.
5.0 M MgCl2-6H2O
Weigh 50,8275 g MgCl2x6H2O, add 30-40 mL water and mix to dissolve using a magnetic stirrer bar.
Adjust volume to 50 mL with H2O.
http://en.wikipedia.org/wiki/Magnesium_chloride
http://www.molecularstation.com/pcr/successful-pcr-conditions/
Metal Ion Cofactors and PCR
An essential cofactor for the DNA polymerase in PCR is Magnesium chloride.
Its concentration must be optimized for every primer:template system.
Many components of the reaction bind magnesium ion, including primers,
template, PCR products and dNTPs. The main 1:1 binding agent for magnesium ion
is the high concentration of dNTPs in the reaction.
Because it is necessary for free magnesium ion to serve as an enzyme
cofactor in PCR, the total magnesium ion concentration must exceed the
total dNTP concentration. Typically, to start the optimization process, 1.5 mM
magnesium chloride is added to PCR in the presence of 0.8 mM total dNTPs.
This leaves about 0.7 mM free magnesium for the DNA polymerase.
In general, magnesium ion should be varied in a concentration series from 1.5–4.0 mM in 0.5 mM steps.