title: Effect of Mg2+ and Mn2+ on hydrolysis of calf thymus DNA by pancreatic deoxyribonuclease I.
abstract: Divalent cations are activators for DNA hydrolysis by pancreatic deoxyribonuclease I. Apparent Vm and Km changes have been studied in presence of Mn2+ or Mg2+. The activation process modifies both Vm and Km, their relationship with Mg2+ or Mn2+ being a linear one. Deoxyribonucleotides inhibit the DNA hydrolysis, whether Mg2+ or Mn2+ is the activator; the purine deoxyribonucleotides are more effective as inhibitors than the pyrimidine ones. The effect of some derivatives of adenine has been studied: the inhibition is maximum with 5'-dAMP and minimum with adenine or adenosine. A kinetic mechanism of enzymatic activation by Mn2+ or Mg2+ is discussed.
mesh_terms: D000227:Adenine Nucleotides / Q000494:pharmacology; D000818:Animals; D002417:Cattle; D004247:DNA; D003850:Deoxyribonuclease I; D003851:Deoxyribonucleases / Q000378:metabolism*; D003854:Deoxyribonucleotides / Q000494:pharmacology; D004720:Endonucleases / Q000378:metabolism*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology*; D008345:Manganese / Q000494:pharmacology*; D010179:Pancreas / Q000201:enzymology*; D013950:Thymus Gland / Q000032:analysis
chemical_list: D000227:Adenine Nucleotides; D003854:Deoxyribonucleotides; D008345:Manganese; D004247:DNA; D003851:Deoxyribonucleases; D004720:Endonucleases; D003850:Deoxyribonuclease I; D008274:Magnesium