blunt end ligation - (Jul/30/2008 )
why do we need to add exogenous ATP for a blunt end ligation ?
ATP is included in the buffer. You can add extra if you want, it won't do any harm.
Ligase Reaction Buffer contains ATP, which is essential for the ligation reaction. Repeated freeze-thaw tend to degrade the ATP in the ligase buffer, thereby reducing itsconcentration. Exogenous ATP is added to supplement for the ATP degraded during the freeze thaw procedure.
Its advisable to store the T4 ligase buffer as small aliquots to avoild multiple free thaws.