Photosensitized oxidative DNA damage: from hole injection to chemical product formation and strand cleavage.

ABSTRACT: Oxidatively generated damage to DNA induced by a pyrenyl photosensitizer residue (Py) covalently attached to a guanine base in the DNA sequence context 5'-d(CAT[G1Py]CG2TCCTAC) in aerated solutions was monitored from the initial one-electron transfer, or hole injection step, to the formation of chemical end-products monitored by HPLC, mass spectrometry, and high-resolution gel electrophoresis. Hole injection into the DNA was initiated by two-photon excitation of the Py residue with 355 nm laser pulses, thus producing the radical cation Py*+ and hydrated electrons; the latter are trapped by O2, thus forming the superoxide anion O2*-. The decay of the Py*+ radical is correlated with the appearance of the G*+/G(-H)* radical on microsecond time scales, and O2*- combines with guanine radicals a

SUBMITTER: Yun BH 

PROVIDER: S-EPMC2519169 | biostudies-literature | 2007 Aug

REPOSITORIES: biostudies-literature