Dear Stefan,
just saw this after reading post:
http://www.nature.com/nature/journal/v522/n7557/full/nature14559.html
Best, Guenter
Pramod,
You already got good suggestions on how to handle DNA contamination in protein
preparations.
Let me point out briefly that you haven't demonstrated yet that your
contamination is DNA.
I had the same observation when purifying UvsX. A very persistent and strong
contamination in all my preps at ~500kb. To test weather it was DNA or RNA I
boiled the protein 30 minutes and incubated it with DNAase and RNAse and result
was the same. I concluded it was neither RNA nor DNA and continued as if
nothing had happened.
This publication is reporting the same observation:
Formosa and Alberts (1986) "Purification and characterization of the T4
bacteriophage uvsX protein." J Biol Chem. 1986 May 5;261(13):6107-18.
If you ever find out what it is that runs like 500kb DNA on Agarose, please let
me know.
S.
