how to confirm the presence or absence of very small dna (if below 5 bps or bases) in a purified protein sample

uday kumar via methods%40net.bio.net (by udayts from gmail.com)
Wed Feb 3 01:43:06 EST 2010


hi

I purified my protein under acidic conditions pH-4 with the reason that it
will be free from dna. even though its 280 absorption dominates the 260
absorption the 280/260 ratio is always 1.2.

I would doubt that there is some DNA but i could not see any signal on
agarose gel. I am also sure that the DNA is not homogeneous as it is
overexpressed in E.coli which is not a native host.

My concern is to confirm the presence or absence of DNA in the sample.

I also tried Mass spectroscopy. its a failure because of some unknown
reason.

could you please suggest me any method that can prove the presence or
absence of DNA. It would be nice if it is other than mass spectroscopy and
radio labeling.

-- 
With Regards
uday
(u.kumar from fz-juelich.de)


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