Synthesis and photooxidation of oligodeoxynucleotides containing 5-dimethylaminocytosine as an efficient hole-trapping site in the positive-charge transfer through DNA duplexes?

Organic & Biomolecular Chemistry Pub Date: 2011-12-12 DOI: 10.1039/C2OB06642D

Abstract

We have designed and synthesized DNA duplexes containing 5-dimethylaminocytosine (DMAC) to investigate the effects of C(5)-substituted cytosine bases on the transfer and trapping of positive charge (holes) in DNA duplexes. Fluorescence quenching experiments revealed that a DMAC base is more readily one-electron oxidized into a radical cation intermediate as compared with other natural nucleobases. Upon photoirradiation of the duplexes containing DMAC, the photosensitizer-injected hole migrated through the DNA bases and was trapped efficiently at the DMAC sites, where an enhanced oxidative strand cleavage occurred by hot piperidine treatment. The DMAC radical cation formed by hole transfer may undergo specific hydration and subsequent addition of molecular oxygen, thereby leading to its decomposition followed by a predominant strand cleavage at the DMAC site. This remarkable property suggests that the modified cytosine DMAC can function as an efficient hole-trapping site in the positive-charge transfer in DNA duplexes.

Graphical abstract: Synthesis and photooxidation of oligodeoxynucleotides containing 5-dimethylaminocytosine as an efficient hole-trapping site in the positive-charge transfer through DNA duplexes
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