A broad-specific alkaline DNase from rat brain with a putative role in DNA excision repair.

An alkaline endodeoxyribonuclease from rat brain has been purified to near homogeneity. The purified enzyme showed a M.Wt. of 54 Kd on SDS-PAGE and does not require metal ion for activity and thus differs from classical DNase I. No preference towards any particular form of calf thymus DNA (native, denatured, undamaged and damaged by exposure to UV, H2O2 and OsO4 and depurination) was noticed. However, with supercoiled pBR 322 plasmid DNA as substrate, higher activity was exhibited towards UV irradiated and depurinated forms. It is suggested that this DNase may be a 'housekeeping' enzyme to detect any conformational distortion in DNA and initiate excision repair.