question (Kate Chabarek)

Hi Kate.

Do you know the amino acid sequence of your protein? If it has much more Phe
than Trp or Tyr, then it should have a max absorbance value at 260 (your
protein might be pure). Otherwise, it may be contaminated with DNA or RNA.
If you cannot see the DNA in agarose, then the nucleic acid contaminants may
be of low MWs (try PAGE stained with Et-Br to confirm). Try dialysis using
tubes with fixed MWCO to remove your contaminants, or try filtration (we use
centriplus from millipore in our lab).

Hope this helps.

Clement