Qiagen Maxiprep Problem

Benny Lo benny at holmes.cancres.nottingham.ac.uk
Tue Apr 4 18:12:20 EST 2000

I have been using Qiagen Maxiprep to prepare plasmids for transfection and
the yield hasn't been too satisfactory. Recently, I found that when I let
the drop of ethanol that sticks on the side of tube evaporate off after IPA
precipitation and EtOH wash, a while precipitate forms where that droplet
sticks. This has led me to think that maybe the DNA has not been
sufficiently precipitated out of the solution. Is that a possibility?

I used 150mL of E coli culture and get only about 100 micrograms of plasmid
out. Given my experience described above, is there any way I can improve the

I also notice some white precipitate that has probably co-precipitated with
the DNA but will not redissolve on the addition of Tris, even after warming
to 37 degrees for a period of time. Very often I just have to spin it down
and take the supernatant as the DNA. Does anyone else experience this also?

Any advice will be appreciated. Many thanks.

More information about the Methods mailing list