Single-stranded DNA preps

Sat Oct 16 09:15:43 EST 1993

I'm having problems isolating single-stranded DNA from M13 phage.
I've tried both mini and large preps but the DNA I've obtained has
always migrated differently. I've been told that on a regular 1%
agarose gel, the ss DNA molecule should move to roughly 3.5 kb. I've
gotten this from a mini-prep but both my large preps so far have
given me DNA that migrates slower than 23 kb (which I presume is
genomic E. coli DNA) and something moving to about 9 kb.  In my
protocol, I made absolutely sure there were no bugs, so I'm wondering
how this can be genomic or any double-stranded DNA. And is it possible
for ssM13 DNA to migrate that slow or is there any truth to the fact
that ss DNA should always migrate to between 2 and 4 kb on a gel?

bgaa at

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