[Coprecipitation of proteins and DNA-protein complexes with magnesium sarcolysate: research on an association of topoisomerase I and RNA polymerase with DNA].

A specific cosedimentation of proteins and their complexes with DNA at low temperature (M-band technique) has been demonstrated. Model experiments with reconstituted SV40 DNA-topoisomerase I and SV40 DNA-E. coli RNA polymerase complexes demonstrated the potential and capacities of the method. It allows fractionation of DNA-protein complexes from naked DNA and has greater range, higher reproducibility and lower background values than similar methods.