Dynamics of singlet oxygen generation by DNA-binding photosensitizers.
The dynamics of photosensitized singlet oxygen generation in a DNA microenvironment were examined using the DNA-binding photosensitizers berberine and palmatine. These photosensitizers generate singlet oxygen only under interaction with DNA because the singlet excited state deactivates rapidly in a nonbinding environment. A kinetic study demonstrated the reaction process whereby singlet oxygen is generated through energy transfer from the triplet excited state of DNA-binding berberine (or palmatine) to molecular oxygen. The guanine-containing sequence of DNA slightly deactivated the singlet excited state of the photosensitizers, resulting in a decrease of the singlet oxygen yield. By the steric hindrance of the DNA strand, the rate constant of the singlet oxygen generation became smaller than that of the other water-soluble photosensitizer.
Department of Basic Engineering (Chemistry), Faculty of Engineering, Shizuoka University, Johoku 3-5-1, Naka-ku, Hamamatsu, Shizuoka 432-8561, Japan. tkhirak@ipc.shizuoka.ac.jp
Kazutaka
K
Hirakawa
Toru
T
Hirano
Yoshinobu
Y
Nishimura
Tatsuo
T
Arai
Yoshio
Y
Nosaka
D004247:DNA / Q000737:chemistry*; D017319:Photosensitizing Agents / Q000737:chemistry*; D026082:Singlet Oxygen
D017319:Photosensitizing Agents; D026082:Singlet Oxygen; D004247:DNA