Silly Question time.

[Richard P Grant]

Given a plasmid digested with a single cutting enzyme, and not
dephosphorylated, is there an *absolute* requirement for ligase to get
religation?

If there is ATP in the buffer but no ligase, I was under the impression
that such a plasmid would not self-ligate because it requires the enzyme
to exchange phosphates - at least for a standard 6-base cutter.  (For
longer overlaps it's feasible the cut would be 'seen' by the bugs as 2
single-stranded nicks and therefore would get repaired in the bacterium). 

Please put my mind at rest ;)

TIA,

Richard

--
Richard P. Grant  MA  DPhil          University of Oxford | rgrant at molbiol
http://www.molbiol.ox.ac.uk/~rgrant  FFPGP                | .ox.ac.uk
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