Ligation problems

[Joe Doe]

In article <mailman.431.1185659366.11350.methods from net.bio.net>,
 "Virash Gupta" <virashkgupta from gmail.com> wrote:
 I know, I can handle ligations as during my work at UC, San
> Diego, CA USA, while using ligase from Gibco BRL I never faced this
> problem. I need to be suggested with a reliable source of ligase for
> its consistent performance in India keeping in view that ligase from
> other sources might be loosing its activity during transportation.
> Dr V K Gupta
> Virashkgupta from gmail.com


Since you use the word "might be losing activity" it does not look like 
you know that it is loosing activity. Why not monitor a ligation 
reaction on a gel? Take something like lambda Hind III and ligate and 
run a gel.  NEB has a picture of the smear of products you expect in 
their catalog.  Do this as a standard control for every ligation until 
the problem is solved.

Secondly, if you suspect enzyme quality perhaps your restriction enzymes 
also leave nibbled ends etc which contribute to your ligation 
difficulties.