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dc.contributor.authorMargison, Geoffrey P
dc.contributor.authorO'Connor, Peter J
dc.date.accessioned2011-11-02T13:03:44Z
dc.date.available2011-11-02T13:03:44Z
dc.date.issued1975-11
dc.identifier.citationRole of apurinic sites in the resistance of methylated oligodeoxyribonucleotides to degradation by spleen exonuclease. 1975, 151 (2):249-56 Biochem Jen
dc.identifier.issn0264-6021
dc.identifier.pmid1218080
dc.identifier.urihttp://hdl.handle.net/10541/188452
dc.description.abstractThe effect of introducing methyl groups into DNA substrates was studied by using the spleen exonuclease (EC 3.1.4.1), an enzyme which hydrolyses oligonucleotides in a sequential manner by splitting off 3'-phosphomononucleotides starting from the 5'-hydroxyl terminus. Analyses of oligodeoxyribonucleotide 3'-phosphate substrates after reaction in vitro with dimethyl sulphate demonstrated that the resultant methylation pattern differed from the previously found for native DNA, particularly with respect to the relative amounts of 1- and 3-methyladenine produced. Although after treatment with increasing amounts of dimethyl sulphate the substrate became progressively resistant to degradation by the exonuclease, the methylation products themselves were only partially responsible for the observed inhibition of enzyme activity. The incomplete degradation encountered was apparently due to the presence of apurinic sites, which arose as secondary lesions after the spontaneous release of the labile alkyl purines from the methylated substrate. Inhibition of enzyme activity appeared to be competitive, being characterized by constant values for apparent Vmax, and increased values for apparent Km. the interpretation of this, however, is complicated by the complex nature of the substrate, and these aspects are considered in some detail.
dc.language.isoenen
dc.subject.meshAdenine
dc.subject.meshBinding Sites
dc.subject.meshBinding, Competitive
dc.subject.meshChromatography, Gel
dc.subject.meshChromatography, Paper
dc.subject.meshDNA
dc.subject.meshExonucleases
dc.subject.meshGuanine
dc.subject.meshKinetics
dc.subject.meshMethylation
dc.subject.meshOligodeoxyribonucleotides
dc.subject.meshOligonucleotides
dc.subject.meshSpleen
dc.subject.meshTime Factors
dc.titleRole of apurinic sites in the resistance of methylated oligodeoxyribonucleotides to degradation by spleen exonuclease.en
dc.typeArticleen
dc.contributor.departmentPaterson Laboratories, Christie Hospital and Holt Radium Institute, Manchesteren
dc.identifier.journalThe Biochemical Journalen
html.description.abstractThe effect of introducing methyl groups into DNA substrates was studied by using the spleen exonuclease (EC 3.1.4.1), an enzyme which hydrolyses oligonucleotides in a sequential manner by splitting off 3'-phosphomononucleotides starting from the 5'-hydroxyl terminus. Analyses of oligodeoxyribonucleotide 3'-phosphate substrates after reaction in vitro with dimethyl sulphate demonstrated that the resultant methylation pattern differed from the previously found for native DNA, particularly with respect to the relative amounts of 1- and 3-methyladenine produced. Although after treatment with increasing amounts of dimethyl sulphate the substrate became progressively resistant to degradation by the exonuclease, the methylation products themselves were only partially responsible for the observed inhibition of enzyme activity. The incomplete degradation encountered was apparently due to the presence of apurinic sites, which arose as secondary lesions after the spontaneous release of the labile alkyl purines from the methylated substrate. Inhibition of enzyme activity appeared to be competitive, being characterized by constant values for apparent Vmax, and increased values for apparent Km. the interpretation of this, however, is complicated by the complex nature of the substrate, and these aspects are considered in some detail.


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