I have problem. I tried to culture plasmid from stock, it has SV40 ori (is it low or high copy?) but never got enough yield. I use Invitrogen PureLink Midi Prep. I did Transformation in E. coli Novablue, Novagen; grew very well as expected in LB plate. I did small culture in 5 mL LB medium, 250 rpm, 37C o/n; transferred the culture to larger LB medium about 150 mL, and incubate 250 rpm, 37c, o/n.
I continue to plasmid extraction by this PureLink kit, which I used to use. Usually I don't have any problem at all, but for this STOCK plasmid I always get low concentration plasmid, messy A 260/280, faint-multiple band by electrophoresis. I even tried the whole process from transformation once.
What's wrong with my protocol??
Oh yeah, I even tried new-unopened kit.