tailieunhanh - Báo cáo khoa học: Ascorbic acid induces a marked conformational change in long duplex DNA

Ascorbic acid is often regarded as an antioxidantin vivo, where it protects against cancer by scavenging DNA-dam-aging reactive oxygen species. However, the detailed mech-anism 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 observa-tion 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. . | Eur. J. Biochem. 270 3101-3106 2003 FEBS 2003 doi Ascorbic acid induces a marked conformational change in long duplex DNA Yuko Yoshikawa1 5 Mari Suzuki1 Ning Chen2 Anatoly A. Zinchenko2 Shizuaki Murata2 5 Toshio Kanbe3 Tonau Nakai4 Hidehiro Oana4 5 and Kenichi Yoshikawa4 5 1 Department of Food and Nutrition Nagoya Bunri College Japan 2Graduate School of Environmental Studies Nagoya University Japan 3Laboratory of Medical Mycology Research Institute for Disease Mechanism and Control Nagoya University School of Medicine Japan 4Department of Physics Kyoto University Japan CREST Core Research for Evolutional Science and Technology of Japan Science and Technology Corporation Ascorbic acid is often regarded as an antioxidant in vivo where it protects against cancer by scavenging DNA-dam-aging 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. Keywords ascorbic acid higher order structure of DNA pearling structure single molecular observation. Vitamin C ascorbic acid is ubiquitous and fundamental in living cells where it acts as a water-soluble antioxidant and an essential cofactor for many enzymes involved in diverse metabolic pathways. Several epidemiological and experimental studies have shown that the consumption of foods rich in vitamin C is associated with a decreased risk of .

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