Mg(OAc)2 instead of MgCl2? - (Jul/27/2005 )

Why is Mg(OAc)2 used in long fragment PCR instead of MgCl2?

Hi,

I don't know the answer to your question, but I was just wondering about the same kind of thing.
Certain enzymes have MgCL2 in their buffer, others MgSO4 and others Mg(OAc)2.


As I have optimised a PCR with an enzyme using MgSO4 in its buffer and am now going to use a one-step RT-PCR that also contains MgSO4, but a lower concentration (the DNA polymerase is the same as in the PCR). When looking closer, the RT enzyme itself (when you buy it as an RT an not in a one step RT-PCR kit) contains MgCL2 (and in a higher concentration than the one I need in my PCR so the Mg concentration is definately higher than in the one step kit).

I conclude that high concentrations of Mg are okay for my RT, but are high concentrations of SO4 okay for my RT?
And can I add MgCL2 to my one-step reaction (can substitution of SO4 with Cl2 have side-effects on my polymerase)? (I'm talking about Superscript III, superscript III one step with platinum taq high fidelity and platinum taq high fidelity).

The weirdest thing of all is that certain enzymes use MgCL2, the RT uses MgCL2 but a one-step kit containing the both of them contains MgSO4. (talking about Superscript III, superscript III one step with platinum taq and platinum taq itself)

Any help/advice greatly appreciated.

(I have contacted invitrogens techical support and am now trying a pcr with MgCl2 instead of MgSO4, I'll let you know the results if anyone is interested).

Edit: done PCR with MgCl2 instead of MgSO4 and get reduced yield, so I'll stick to MgSO4 for PCR.

basically, only the Mg should be the important part, but nobody can rule out some side effects like buffering abilities of the anion or something...

mike