title: An endonuclease from calf liver specific for apurinic sites in DNA.
abstract: An endonuclease specific for apurinic sites in double-stranded DNA has been partially purified from calf liver extracts. The enzyme has a pH optimum of 9.5, is only slightly stimulated by low concentrations of Mg2+, and has a molecular weight of 28 000. Inhibitors of the endonuclease include Ca2+, EDTA, p-HOHgBzO, NaCl, and tRNA. The enzyme introduces single- and double-stranded breaks in depurinated DNA. High concentrations of the enzyme preparation degrade untreated single-stranded DNA, but not ultraviolet (UV) irradiated DNA or DNA treated with methylmethanesulfonate or 7-bromomethyl-12-methylbenz[a]-anthracene. Enzymatic incisions produce 3'-hydroxyl and 5'-phosphate end groups. Some of the properties of the calf liver apurinic endonuclease differ from those of a similar endonuclease obtained from calf thymus by S. Ljungquist and T. Lindahl [(1974), J. Biol. Chem. 249, 1530] and in this laboratory. The data suggest that these are isozymes.
mesh_terms: D000818:Animals; D002417:Cattle; D004247:DNA; D003851:Deoxyribonucleases / Q000302:isolation & purification / Q000378:metabolism; D004720:Endonucleases / Q000302:isolation & purification / Q000378:metabolism; D006902:Hydroxymercuribenzoates / Q000494:pharmacology; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D010084:Oxidation-Reduction; D011687:Purines / Q000032:analysis; D013997:Time Factors
chemical_list: D006902:Hydroxymercuribenzoates; D011687:Purines; D004247:DNA; D003851:Deoxyribonucleases; D004720:Endonucleases