polynucleotide kinase

[kim at m44.unm.edu]

Hello:
   I am trying to do polynucleotide kinase exchange reactions on RNA.  In the
protocol described in Maniatis and in Current Protocols, exchange reactions are
distinguished from the 'forward reaction' by the use of imidazole buffer
instead of TRIS.  Does anyone know why, an how critical it is to use this
buffer system.  Please send replies to  KIM at FLOVAX.LANL.GOV  

Thanks
Daniel Kim