Figure 9.

Alkylation of 5-methylcytosine-containing duplexes by activated leinamycin. The 5'-³²P-labeled 2'-deoxyoligonucleotide duplexes 16–19 were treated with leinamycin and 2-mercaptoethanol in HEPES (50 mM, pH 7), DETAPAC (5 mM) containing 37% acetonitrile (v/v) at 37 °C for 23.6 h, followed by Maxam-Gilbert workup. The resulting DNA fragments were resolved on a 20% denaturing polyacrylamide gel and visualized by phosphorimager analysis. Lane 1, duplex 16 treated with 2-mercaptoethanol (5 mM and no leinamycin); lane 2, duplex 16 treated with leinamycin (0.2 mM) and 2-mercaptoethanol (0.2 mM); lane 3, duplex 16 treated with leinamycin (0.5 mM) and 2-mercaptoethanol (0.5 mM); lane 4, duplex 16 treated with leinamycin (1 mM) and 2-mercaptoethanol (1 mM); lane 5, duplex 16 treated with leinamycin (5 mM) and 2-mercaptoethanol (5 mM); lane 6, duplex 17 treated with 2-mercaptoethanol (1 mM); lane 7, duplex 17 treated with leinamycin (1 mM) and 2-mercaptoethanol (1 mM); lane 8, duplex 18 treated with 2-mercaptoethanol (1 mM); lane 9, duplex 18 treated with leinamycin (1 mM) and 2-mercaptoethanol (1 mM); lane 10, duplex 19 treated with 2-mercaptoethanol (1 mM); lane 11, duplex 19 treated with leinamycin (1 mM) and 2-mercaptoethanol (1 mM).