DNase I footprinting Deoxyribonuclease I (DNase I) does not have high specificity for given sequences or residues, thus footprinting with DNase I permits the exact delineation of the protein-DNA binding site. Moreover DNase I, can be used for in vivo footprinting by treating intact cells with permeabilising drugs. In this latter case DNase I in vivo footprinting allow studies of the chromatin structure in genomic DNA. PSI-MI DNase I protection MI:0606 dnase 1 footprinting nuclease footprinting