Recognition and Conversion of Single- and Double-Stranded Oligonucleotide Substrates by 8-Oxoguanine-DNA Glycosylase from Escherichia coli

A. A. Ishchenko,¹ N. V. Bulychev,¹ G. A. Maksakova,¹ F. Johnson,² and G. A. Nevinsky^1,3

¹Novosibirsk Institute of Bioorganic Chemistry, Siberian Division, Russian Academy of Sciences, ul. Lavrent'eva 8, Novosibirsk, 630090 Russia; E-mail: nev@modul.bioch.nsk.su

²Department of Pharmacological Sciences, State University of New York at Stony Brook, Stony Brook, NY, 11794-8651, USA.

³To whom correspondence should be addressed.

Submitted October 9, 1996.

The substrate specificity of 8-oxoguanine-DNA glycosylase was studied. The data showed for the first time that the enzyme can cleave single-stranded deoxyoligonucleotides containing an 8-oxoG link. The values of K_m and V_max for a range of single-stranded and double-stranded oligonucleotides (23 bp) containing 8-oxoG at different positions of one chain. These parameters consistently depended on the position of 8-oxoG in single-stranded or double-stranded substrates. A possible mechanism responsible for substrate recognition by 8-oxoguanine-DNA glycosylase is described.

KEY WORDS: 8-oxoguanine-DNA glycosylase, single-stranded oligonucleotides, substrate specificity.

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