Tailed primer

[sdelandtsheer]

Hello

I would like to use tailed primers in PCR. The purpose is to use the "primer extension" technique, in which you PCR only with ddNTPs, so you extend with only one single base (which is a SNP that you want to analyse).

My poblem is that I need quite long primers (about 50-60bp) in order to be able to precipitate them.

My solution, my problem :
- I want to use tailed primers for mass-tagging purposes, then I need any sequence. Should I use poly-A, poly-G, poly-smth else, M13 sequence? I just need something neutral in fact, with a different lenght for each of the (+-20) primers in my multiplex.

Can you help ?

Thank you in advance...