Photoinduced electron transfer and strand cleavage in pyrenyl–DNA complexes and adducts

✍ Scribed by Nicholas E. Geacintov; Kyril Solntsev; Lawrence W. Johnson; Junxin Chen; Alexander D. Kolbanovskiy; Tongming Liu; Vladimir Ya. Shafirovich

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 149 KB
• Volume: 11
• Category: Article
• ISSN: 0894-3230
• DOI: 10.1002/(sici)1099-1395(199808/09)11:8/9<561::aid-poc61>3.0.co;2-a

✦ Synopsis

The fluorescence of pyrenyl residues in complexes with the nucleic acid bases G, C and T, but not A, is strongly quenched by photoinduced electron transfer mechanisms. Site-specifically modified 11-mer oligonucleotide duplexes containing a single modified guanosyl base G* bearing a covalently attached pyrenyl residue were prepared in order to probe for photochemical damage associated with these photoinduced electron transfer reactions. When the pyrenyl residue positioned at G* is photoexcited with 355 nm light, direct strand cleavage is observed at that site with low quantum yield. Frank strand breaks are also observed up to five base pairs away from G*, suggesting that intrastrand migration of a reactive intermediate from base to base is occurring.