Why is mgcl2 used in pcr

During the elongation step of the PCR, the primer has to anneal or stick properly to the template and this is facilitated by the KCl. Thus, it functions by reducing the repulsion between the negatively charged DNA strands i.

The temperature that is used during the annealing step of the PCR is less definitive and the salt helps in the annealing of the primer so the polymerase can start adding nucleotides from the bound primer properly. Increasing the KCl concentration have shown to result in longer double stranded DNA to be reluctant in separating i. Cheng et al. Increasing the KCl concentration to 70mM - mM from the normal concentration in the PCR buffer of 50mM was shown to result in the improved yield of small sized products.

It is to be noted that the polymerase enzyme's storage buffer generally contains mM KCl and this should be kept in mind since it can result in variation of final concentration of KCl. It interacts with by means of hydrogen bonds. However, if inhibitors are present in the reaction mix eg, if the template DNA used is not highly purified , higher amounts of Taq DNA polymerase 0.

The range of MgCl 2 usually is from 0. High MgCl 2 concentrations can help to stabilize interaction of the primers with their intended template if it is not being amplified, but can also result in nonspecific binding and erroneous PCR product formation.

The amount of additional MgCl 2 must be carefully monitored. Salt and buffers - Stabilize enzyme function and formation of primer-template hybrids. Which cookies and scripts are used and how they impact your visit is specified on the left.

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