Many of these DNA-binding proteins are very strongly positively charged.

I have purified such proteins in the past running the cell lysate over a cation exchange column at pH 7 to pH 8.

At these pH-values, practically only DBA-binding proteins will bind to the resin and you still have to use a rather high salt concentration to get them off again. The proteins coming off are rather pure after just this one step.

Thanks Achim for your kind advise.

Can you share the formula of your lysis buffer

These were different, depending of the host organism.

I usually had my cell suspension and used at small-scale a sonicator at large-scale (manufacturing scale) a high-pressure homogenizer.

If I remember correctly, at small-scale - probably the more interesting for you :) - I centrifuged the cells and suspended them in a PBS-like buffer (e.g., 25mM phosphate, pH 7) before sonication.

I did all my work with microbial hosts. In case you use mammalian cells, you may have to adapt the sample matrix.

Hi Hui,

I've done histone purification before, and a related article recommended to you

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2699528/

Hope it helps!

Hi Roger,

It also helps.

Thank you

In my first answer, I wrote that many chromatin-binding proteins are highly positively charges, as they bind to the DNA. But I forgot to mention, you may also have proteins binding to chromatin that are hydrophobic; the parts of the histones not covered by bound DNA is hydrophobic.