Ascorbic acid induces a marked conformational change in long duplex DNA.
Ascorbic acid is often regarded as an antioxidant in vivo, where it protects against cancer by scavenging DNA-damaging reactive oxygen species. However, the detailed mechanism of the action of ascorbic acid on genetic DNA is still unclear. We examined the effect of ascorbic acid on the higher-order structure of DNA through real-time observation by fluorescence microscopy. We found that ascorbic acid generates a pearling structure in single giant DNA molecules, with elongated and compact regions coexisting along a molecular chain. Results from electron microscopy and atomic force microscopy indicate that the compact regions assume a loosely packed conformation. A possible mechanism for the induction of this conformational change is discussed in relation to the interplay between the higher-order and second-order structures of DNA.
Yoshikawa
Yuko
Y
Department of Food and Nutrition, Nagoya Bunri College, Japan. yuko@chem.scphys.kyoto-u.ac.jp
Suzuki
Mari
M
Chen
Ning
N
Zinchenko
Anatoly A
AA
Murata
Shizuaki
S
Kanbe
Toshio
T
Nakai
Tonau
T
Oana
Hidehiro
H
Yoshikawa
Kenichi
K
D001205:Ascorbic Acid / Q000494:pharmacology*; D017122:Bacteriophage T4 / Q000737:chemistry / Q000235:genetics; D002942:Circular Dichroism; D004279:DNA, Viral / Q000737:chemistry* / Q000648:ultrastructure; D008853:Microscopy / Q000379:methods; D008958:Models, Molecular; D009690:Nucleic Acid Conformation / Q000187:drug effects*
D004279:DNA, Viral; D001205:Ascorbic Acid