Hydrolysis of carcinogen-dna adducts by three classes of deoxyribonucleosidase to their corresponding bases

Zigang Dong, Alan M. Jeffrey

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4 Scopus citations

Abstract

We have investigated three different enzymes, each of which splits the glycosidic bonds of normal deoxyribonucleosides, for their ability to cleave acid-sensitive carcinogen-DNA adducts: Leishmania donovani purine deoxyribonucleosidase; Lactobacillus helveticus trans-N-deoxyribosyiase; and purine nucleoside phosphorylase. Twenty-eight substrates were assayed using one or more of the enzymes, monitoring free base formation by reverse-phase HPLC and a diode array detector. Products were characterized by their retention times and UV spectra. The deoxyribonucleosidase showed the broadest specificity: substrates cleaved by either the trans-N-deoxyribosylase or the phosphorylase were hydrolyzed by the deoxyribonucleosidase. O6-and N2-alkyldeoxyguanosine, N6-alkyl deoxyadenosine and several cyclic adducts were all hydrolyzed by the deoxyribonucleosidase. None of these enzymes cleaved three bulkier adducts; N2-, N6- and C-8 derivatives of benzo[a]pyrene, benzo[c]phenanthrene and N-acetoxy-2-acetylamlnofluorene, respectively. Only the deoxyribonucleosidase hydrolyzed O6-methyldeoxyguanosine while both the deoxyribonucleosidase and trans-N-deoxyribosylase cleaved N6-methyl deoxyadenosine. These enzymes, especially the deoxyribonucleosidase, provide mild ways to release the carcinogen-modified base from deoxyribose and will be useful in DNA adducts analysis.

Original languageEnglish (US)
Pages (from-to)1125-1128
Number of pages4
JournalCarcinogenesis
Volume12
Issue number6
DOIs
StatePublished - Jun 1 1991

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