title: DNase VII of human placenta. Mechanism studies.
abstract: The mechanism of the human placental DNase VII, described previously (Hollis, G. F., and Grossman, L. (1981) J. Biol. Chem. 256, 8074-8079) has been investigated in further detail. The enzyme initiates exonucleolytic hydrolysis from the 3'-end of DNA in a nonprocessive, or distributive, manner, regardless of whether the carbohydrate moiety associated with the 3'-terminal nucleotide contains H or OH at its 2' and 3' positions. DNase VII does not have associated RNase H activity; however, it is capable of removing 3'-terminal ribonucleotides. The enzyme also can hydrolyze DNA containing a terminal nucleotide lacking a purine or pyrimidine as well as termini containing noncomplementary nucleotides. DNase VII activity is product-inhibited by deoxynucleoside 5'-monophosphates. From kinetic studies, the mononucleotide deoxyadenylic acid is a noncompetitive inhibitor with a Ki = 0.3 mM. The resemblance of DNase VII to the 3'----5' exonuclease activity of Escherichia coli DNA polymerase I and its possible role in excision repair and proofreading are discussed.
mesh_terms: D004247:DNA / Q000032:analysis; D045647:DNA Glycosylases; D004256:DNA Polymerase I / Q000378:metabolism; D003838:Deoxyadenine Nucleotides / Q000494:pharmacology; D003839:Deoxyadenosines / Q000032:analysis; D004926:Escherichia coli / Q000201:enzymology; D005090:Exodeoxyribonucleases / Q000378:metabolism*; D005260:Female; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics; D009699:N-Glycosyl Hydrolases / Q000378:metabolism; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D013997:Time Factors
chemical_list: D003838:Deoxyadenine Nucleotides; D003839:Deoxyadenosines; C012873:2'-deoxy-5'-adenosine monophosphate; D004247:DNA; D004256:DNA Polymerase I; D005090:Exodeoxyribonucleases; C026870:exodeoxyribonuclease VII; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases