Dear Uday, Actually, the A280/A260 ration depends on the individual AA composition of your protein.
5 bp DNA should be roughly 1 kDa in size, so it might be removable by dialysis or ultrafiltration as log as it does not bind too strong. If you suspect your protein binds specifically small junks of DNA, the situation is more difficult. If it is non-specific binding, you might be able to demonstrate the effect by affinity chromatography on immobilized DNA or oligos. If you think that your protein has bound some DNA, you maybe can detect it by fluorescence: Either autofluorescence of DNA or binding (and or change of fluorescence properties) of dyes like ethidiumbromide, propidiumiodide, H33258, DAPI, SybrGreen and so on. If you know the identity of your protein (i.e. if you can get hold of the AA sequence) life will be easier. In order to determine the sequence of the bound DNA, try to clone and sequence it. If you just need to make sure that your protein preparation does not contain any DNA, try an appropriate DNAse. HTH Wo _______________________________________________ Methods mailing list [email protected] http://www.bio.net/biomail/listinfo/methods
