purifying with glassmilk

Thu Oct 3 13:04:10 EST 1991

 purifying with glassmilk does introduce breaks in the DNA. The problem
exists with closed circular plasmids, long linear DNA, and single-strand
DNA. I was able to nearly eliminate breakage of single-strand M-13 type
phage by doing the following:
 1. Use more of the iodide solution than the manual calls for. You can't
    add too much. The more you add, the better single-strand DNA sticks.
 2. DON'T CENTRIFUGE. Let the glassmilk settle out by gravity. If you
    use a large volume of wash, this works well. It takes a lot longer,
    but breaks are almost eliminated. The only point I centrifuge at is
    after the final wash when you add water.

-Peter Markiewicz

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