Evidence for two DNA repair enzymes for 8-hydroxyguanine (7,8-dihydro-8- oxoguanine) in human cells

T. Bessho, K. Tano, H. Kasai, E. Ohtsuka, S. Nishimura

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Abstract

Two DNA repair enzymes for 8-hydroxyguanine (also known as 7,8-dihydro-8- oxoguanine; OH8Gua, oxo8Gua) have been identified in human HeLa cell nuclear extract. One is OH8Gua-glycosylase and the other is OH8Gua- endonuclease that lacks OH8Gua-glycosylase activity. They were separated by heparin-Sepharose column chromatography and characterized by endonuclease nicking assay or by measuring the OH8Gua released from substrate DNA using high pressure liquid chromatography-electrochemical detection. Both OH8Gua repair enzymes act only on the OH8Gua-containing strand of the duplex substrate DNA containing OH8Gua/C, OH8Gua/T, or OH8Gua/G. DNA containing OH8Gua/A base pair was very poor substrate for either enzymes. OH8Gua- endonuclease simultaneously cleaves phosphodiester bonds on both sides of the OH8Gua residue, leaving 5'-hydroxy and 3'-hydroxy groups.

Original languageEnglish (US)
Pages (from-to)19416-19421
Number of pages6
JournalJournal of Biological Chemistry
Volume268
Issue number26
StatePublished - Jan 1 1993

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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