Salt for annealing oligos - (Aug/22/2007 )

Hi!

I wonder why is it important to have at least 50mM NaCl when annealing oigos?

Thanks!

Hi Olgam

The reason is that the phosphate backbone of DNA is negatively charged so single-standed DNA, such as your oligos, will slightly repel each other, preventing or at least inhibiting annealling. In solution, NaCl dissociates to give Na+ and Cl-. The Na+ associates with the negatively charged phosphate groups, neutralizing the charge and allowing the strands to come together.

Nick.

thank you, Nick!
Olga