title: Bivalent cation and ATP requirements of endonucleases from rat liver nuclei.
abstract: The distribution of different types of DNase in rat liver nuclei was determined after a purification procedure involving ion exchange chromatography and gel filtration. As major enzymes Ca2+, Mg2+-dependent endonuclease, Mn2+-dependent endonuclease and an acid endonuclease were identified, sharing 60, 20 and 10% of the total activity, respectively. Mn2+-dependent endonuclease is a novel enzyme with a molecular mass of 30 +/- 5 kilodaltons. The synergistic effect of Ca2+ and Mg2+ ions for the Mn2+-dependent enzyme was lower by an order of magnitude than that of the Ca2+ and Mg2+-dependent endonuclease. The Ca2+ and Mg2+-dependent nuclease activity represents a heterogeneous population of enzymes. One of the cation dependent enzymes (Mr 25 +/- 5 kD) is stimulated by ATP the ATP optimum being 0.1 mM and the Mg2+ requirement 1 mM. The ATP-dependent endonuclease belongs to the minor endonucleases separable from the major ones.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002413:Cations, Divalent; D002467:Cell Nucleus / Q000201:enzymology*; D004706:Endodeoxyribonucleases / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D008345:Manganese / Q000494:pharmacology; D008970:Molecular Weight; D051381:Rats
chemical_list: D002413:Cations, Divalent; D008345:Manganese; D000255:Adenosine Triphosphate; D004706:Endodeoxyribonucleases; D008274:Magnesium; D002118:Calcium