Synthesis and stereochemical assignment of DNA spore photoproduct analogues

Marcus G. Friedel, J. Carsten Pieck, Jochen Klages, Christina Dauth, Horst Kessler, Thomas Carell

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26 Scopus citations

Abstract

Investigation of the DNA repair process performed by the spore photoproduct (SP) lyase repair enzyme is strongly hampered by the lack of defined substrates needed for detailed enzymatic studies. The problem is particularly severe because the repair enzyme belongs to the class of strongly oxygen-sensitive radical (S)-adenosyl-methionine (SAM) enzymes, which are notoriously difficult to handle. We report the synthesis of the spore photoproduct analogues 1a and 1b, which have open backbones and are diastereoisomers. In order to solve the problem of stereochemical assignment, two further derivatives 2a and 2b with closed backbones were prepared. The key step of the synthesis of 2a/b is a metathesis-based macrocyclization that strongly increases the conformational rigidity of the synthetic spore photoproduct derivatives. NOESY experiments of the cyclic isomers furnished a clear cross-peak pattern that allowed the unequivocal assignment of the stereochemistry. The results were transfer red to the data for isomers 1a and 1b, which were subsequently used for enzymatic-repair studies. These studies were performed with the novel spore photoproduct lyase repair enzyme from Geobacillus stearothermophilus. The studies showed an accordance with a recent investigation performed by us with the spore photoproduct lyase from Bacillus subtilis,[1] in that only the 5 isomer la is recognized and repaired. The ability to prepare a defined functioning substrate now paves the way for detailed enzymatic studies of the SP-lyase lesion recognition and repair process.

Original languageEnglish
Pages (from-to)6081-6094
Number of pages14
JournalChemistry - A European Journal
Volume12
Issue number23
DOIs
StatePublished - 7 Aug 2006

Keywords

  • Cyclization
  • DNA damage
  • Enzymes
  • Spore photoproduct
  • Structure elucidation

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