title: Enzymatic activation of DNA cleavage by dynemicin A and synthetic analogs.
abstract: Dynemicin A (1), a member of the enediyne family of natural products, binds to double-stranded DNA (K(B) approximately 10(4) M(-1)) and in the presence of millimolar concentrations of a reducing cofactor such as NADPH or GSH reacts to cleave DNA. In this work, we show that the two flavin-based enzymes ferredoxin-NADP+ reductase and xanthine oxidase catalyze the reductive activation of 1 by NADPH and NADH, respectively. The enzyme-catalyzed reductive activation of 1 leads to more rapid and efficient cleavage of DNA, even with 10-20-fold lower concentrations of the stoichiometric reductant. Significantly, the enzymatic systems are also found to activate the tight-binding (K(B) > or = 10(6) M(-1)) synthetic dynemicin analogs 3 and 5 toward DNA cleavage. These same analogs do not undergo reductive activation with NADPH or NADH alone, where evidence has been obtained to support the proposal that the DNA-bound drugs are protected from reductive activation. The new enzymatic activation processes described may have important implications for chemistry occurring with 1 and synthetic analogs in vivo, as well as for the future development of dynemicin-based anticancer agents.
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena 91125, USA.
authors.forename: A G
authors.initials: AG
authors.lastname: Myers
authors.forename: M E
authors.initials: ME
authors.lastname: Kort
authors.forename: S B
authors.initials: SB
authors.lastname: Cohen
authors.forename: N J
authors.initials: NJ
authors.lastname: Tom
mesh_terms: D000880:Anthraquinones / Q000378:metabolism / Q000494:pharmacology; D000903:Antibiotics, Antineoplastic / Q000378:metabolism / Q000494:pharmacology; D001711:Biotransformation; D004247:DNA / Q000378:metabolism*; D004262:DNA Restriction Enzymes / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D053281:Enediynes; D005287:Ferredoxin-NADP Reductase / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism; D015394:Molecular Structure; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D014969:Xanthine Oxidase / Q000378:metabolism*
chemical_list: D000880:Anthraquinones; D000903:Antibiotics, Antineoplastic; D053281:Enediynes; D009243:NAD; D009249:NADP; D004247:DNA; C061229:dynemicin A; D014969:Xanthine Oxidase; D005287:Ferredoxin-NADP Reductase; D004262:DNA Restriction Enzymes; D005978:Glutathione