4+2 rule

Robert Darnell darnelr at rockvax.rockefeller.edu
Thu Aug 1 18:25:22 EST 1996

Hello all:

I am wondering whether the 4+2 rule actually applies to oligo conditions
that we frequently use (for PCR, sequencing, etc).  Specifically, "it has
been said" that the 4+2 rule applies to Tm's under 1M salt conditions,
which would essentially invalidate it (Tm-16.6) for most applications. 
The noly ref to a reference that I have found was to an old NAR paper that
didn't discuss this at all.


Who knows the origin of the 4+2 rule, and/or what annealing conditions it
was designed to apply to?


bob darnell

Bob Darnell
Rockefeller University
New York, NY

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