Why 5'->3' and not 3'->5' ?

[Scott McMahan]

In article <slrn6hm0r0.b70.adhar at elaine44.Stanford.EDU>,
adhar at stanford.edu.XX (Adam Noel Harris) wrote:

:Yes, but why is the triphosphate group not off the 3' end? :)

I wish I knew.  I'm sure it is somewhat related to the fact that chemistry
is not random, but I can't say why it would be favored off the 5' end and
not the 3' end.  Does anyone know?

-- 
                                         Scott McMahan
                                         mcmahan at oncology.wisc.edu