Why anneal at Tm? - (Dec/28/2007 )

If only half of the primers are meant to be annealed at this temperature then why isn't a lower annealing temperature used? Is preventing secondary annealing the major reason or are there others?

Cheers, Rob

Typically a lower temperature *IS* used, around 4-6 degrees lower.

i use these kind of pcr protocols, for long primers or primers showing intracomplementary sequences.

these higher tm are used also in case of DMSO incompatible polymerases.