What is the function of MgCl2 in PCR?

Q: What is the function of MgCl2 in PCR?

In PCR, MgCl2 is an essential cofactor that enhances the activity of Taq DNA polymerase, which in turn increases the amplification rate of DNA. It is important to note, however, that higher concentrations of MgCl2 can result in decreased specificity. In addition, MgCl2 also helps primers anneal to the correct location on a DNA template; this is due to Mg2+ binding to the negatively charged phosphate groups in DNA, thereby decreasing electrostatic repulsion between strands.

Posted May 9, 2020

Polymerase Chain Reaction (PCR)

Polymerases

magnesium

Answer

In PCR, MgCl₂ is an essential cofactor that enhances the activity of Taq DNA polymerase, which in turn increases the amplification rate of DNA. It is important to note, however, that higher concentrations of MgCl₂ can result in decreased specificity. In addition, MgCl₂ also helps primers anneal to the correct location on a DNA template; this is due to Mg²⁺ binding to the negatively charged phosphate groups in DNA, thereby decreasing electrostatic repulsion between strands.

Additional resources

Schmidt, G., Stiverson, J., Angen, Ø., & Yu, Z. (2014). Number of PCR cycles and magnesium chloride concentration affect detection of tet genes encoding ribosomal protection proteins in Swine manure. Advances in Microbiology, 2014.