Maxiprep woes

Michael Tomasson tomasson at
Thu Feb 1 15:51:37 EST 1996

Greetings gang,

A "simple" question...I am having a strange problem with my maxi-
prep of a new pUC9 based vector, about 9 kb in size.  I get a zero
yield with my maxi-prep using QIAGEN reagents.  Now, I've done a
bunch of gels to figure out where things are going wrong, and get
this-- I can miniprep the plasmid just fine from a 200 cc LB
culture.  But when I alkaline lyse a larger volume (using the SAME
reagents used in the miniprep) and precipitate the DNA, I get
nothing.  So I figure for some reason the plasmid is coming down
with the bacterial DNA/salt/high weight RNA junk that precipitates
after the addition of potassium acetate/neutralization buffer.

Has anyone ever heard of this happening?  It doesn't happen with
any other vector I have used.  Can anything be done about this?

Michael T.

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