title: Partial purification and characterization of four endodeoxyribonuclease activities from Escherichia coli K-12.
abstract: Four hitherto undescribed endodeoxyribonucleases, temporarily designated A(1), A(2), A(3), and B, have been isolated from E. coli K-12. Each requires Mg(++) and is not stimulated by ATP or S-adenosylmethionine. A(3) is strongly inhibited by Fe(+++) and weakly inhibited by ATP, S-adenosylmethionine, and DPN, whereas B is inhibited by caffeine. Each can be purified free of exonuclease or DNA-3'-phosphatase. A(1) (molecular weight approximately 72,000) cleaves single-stranded, circular fd DNA to form 3'-hydroxyl termini and introduces nicks and breaks in the closed, double-stranded replicative form DNA of fd (fd RFI). A(2) (molecular weight approximately 46,000) cleaves fd DNA and introduces nicks and breaks in RFI, forming 3'-hydroxyl- and 5'-phosphoryl termini. A(3) (molecular weight approximately 38,000) cleaves fd DNA to form 3'-hydroxyl termini and introduces only nicks in fd RFI. Irradiation of the RFI with ultraviolet light markedly increases the rate of hydrolysis by A(3). B appears to form 3'-phosphoryl termini with fd DNA, but its characterization is highly preliminary due to its instability.
authors.forename: R V
authors.initials: RV
authors.lastname: Blackmore
authors.forename: S
authors.initials: S
authors.lastname: Linn
mesh_terms: D011232:Chemical Precipitation; D002845:Chromatography; D004279:DNA, Viral / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D017912:Inovirus; D007700:Kinetics; D008970:Molecular Weight; D013379:Substrate Specificity
chemical_list: D004279:DNA, Viral; D004706:Endodeoxyribonucleases