Rescuing plasmid from dead E.coli stock.

[Emma Macfarlane]

I remember reading some time ago on this newsgroup about retreiving 
plasmid from dead plates to re-transform into E.coli, but I can't
find reference to it in the archives. Is it possible to
do the same thing with frozen stocks? We have an important construct 
in a sickly E.coli strain that is now refusing to grow. I tried
taking a scraping of cells, boiling it up in water, spinning it down
and using the supernatant to transform DH5a. This didn't work.
If anyone has an alternative suggestion I would appreciate hearing it.
Please reply direct to my email address emma at hancock.microbiology.ubc.ca 
as I am not a regular subscriber to the newsgroup.
Thanks in advance
Emma