fresh transformations for protein expression??

Jennifer Lyon JLyon at
Mon Jan 15 18:46:43 EST 1996

Jared wrote:
> I am expressing what I would expect to be non-toxic constructs using the
> pET system, and have had similar problems.  Freshly transformed cells
> express well but after a week siting in the fridge the cells won't
> express at all.  Even the glycerols I have made lost the ability to
> express protein. 

How much glycerol are you using when you make a glycerol stock. We've 
found that 8% is sufficient, and if you use too much glycerol it makes 
plasmids extremely unstable. Just a thought. Sometimes storing down the 
epxression plasmid in the expression host can result in some rather odd 
effects. I'm not sure exactly why, perhaps damage to the lysogen itself.

-------------------------------------------------------------------------JennyAnn at                   JLyon at
"Sometimes the need to mess with their heads outweighs the
millstone of humiliation."  Fox Mulder  "The X-Files"

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