Raman spectroscopic study of DNA photodamage sensitized by hypocrellin B and 5-brominated-hypocrellin B |
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Authors: | Hongxia Zhao Yiming Xu Zhiyi Zhang |
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Institution: | (1) Institute of Biophysics, the Chinese Academy of Sciences, 100101 Beijing, China |
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Abstract: | Hypocrellin B (HB) is a highly effective photosensitizer. One of its derivatives, 5-brominated-hypocrellin B (5-Br-HB) has
better photosensitive characterlstics than it. Using Raman spectroscopy, the microcosmic photodamage to DNA sensitized by
HB and 5-Br-HB was studied at molecular level. The results showed that when HB and 5-Br-HB were added to the solution of DNA
and irradiated, the characteristic Raman frequencies and intensities of DNA changed to various degrees. The photodamage occurred
on the whole DNA molecule, including phosphate backbone, deoxyribose and four bases. Not only the conformation but also the
configuration of DNA was photodamaged: breakage of some H-bonds, disappearance of B-form conformation, scission of double
or single strand and serious damage of four bases. The damage to A-T pairs was stronger than that to C-G pairs and DNA became
polynucleotides finally. The 5-Br-HB-photosensitized damage to DNA was stronger than HB, which suggested the better photosensitive
characteristics of 5-Br-HB in bioactive environment. The molecular mechanisms of photodamage to DNA sensitized by 5-Br-HB
and HB were also elucidated. |
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Keywords: | hypocrellin B 5-brominated hypocrellin B calf thymus DNA photodamage Raman spectroscopy |
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