PCR 10x Taq Buffer with MgCl2

[aria johnson]

Hi Alex,
The Mg ++ neutralizes the replusion between the primer backbone and template
DNA backbone and this affects primer binding stringency. The more Mg you
have the more it neutralizes the repulsion / the better the primer can bind
to the template strand - the less Mg is the more the repulsion between the
primer and template resulting in less primer binding to the template. As a
result, too much MgCl can lead to a lot of non-specific amplification (the
primer can bind to sites with mismatches) while too little MgCl can lead to
no amplification (repulsive forces too much).

Mg is also a cofactor in DNA polymerization - the more Mg is the better the
Taq is able to perform but here again - too much Mg can reduce the Taq
enzyme fidelity while too little can can inactivate the Taq.

As you have asked about components of PCR buffer you should note, MgCl does
not have to be in the 10x Buffer - we use different concn of MgCl in
different reactions and so buy our 10x PCR buffer separate from our MgCl.
take care
Aria

ps there is a good pcr book called PCR Primer: A Laboratory Manual by Cha
and Thilly (1995) that can be helpful and also Molecular Systematics that
can be helpful to you. aj


 On 9/14/06, Alexander Berkow <alexbrkw at gmail.com > wrote:
>
> Can someone out there tell me what the purpose of the MgCl2 in the 10x Taq
> PCR reaction buffer is and what else is in the buffer that is necessary
> for
> the PCR to work correctly?
>
> Thanks!
>
> Alex
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-- 
Aria Johnson
Biological Scientist,
7922 NW 71st Street,
University of Florida
Gainesville Fl. 32653
U.S.A .


-- 
Aria Johnson
Biological Scientist,
7922 NW 71st Street,
University of Florida
Gainesville Fl. 32653
U.S.A.