Alteration in restriction enzyme digestion patterns detects DNA--protein complexes induced by chromate

DNA--protein complexes isolated from CHO cells treated with at least 10-30 microM potassium chromate exhibited an alteration in the degradation of the DNA by restriction enzymes compared to DNA--protein complexes isolated from untreated cells. This alteration in restriction enzyme digestion of DNA--protein complexes induced by chromate was shown to depend upon the binding of trivalent chromium to the DNA and upon the protein associated with the DNA, since both EDTA pretreatment and protease K reversed the inhibition of restriction enzyme degradation of the DNA. The inhibition of restriction enzyme degradation of DNA--protein complexes may be utilized as an indirect way to detect DNA--protein complexing induced by chromate and perhaps other agents.