Xiao Hourong, Xu Xiaolong, Xie Yongshu, Sheng Liangquan, Zhang Yange, Liu Qingliang. Spectroscopic Studies on pH-induced Changes in Secondary Structure of Pophenol Oxidase from Tobacco[J]. Chinese Journal of Chemical Physics , 2004, 17(2): 196-170. doi: 10.1088/1674-0068/17/2/196-170
Citation: Xiao Hourong, Xu Xiaolong, Xie Yongshu, Sheng Liangquan, Zhang Yange, Liu Qingliang. Spectroscopic Studies on pH-induced Changes in Secondary Structure of Pophenol Oxidase from Tobacco[J]. Chinese Journal of Chemical Physics , 2004, 17(2): 196-170. doi: 10.1088/1674-0068/17/2/196-170

Spectroscopic Studies on pH-induced Changes in Secondary Structure of Pophenol Oxidase from Tobacco

doi: 10.1088/1674-0068/17/2/196-170
Funds:  Project supported by the National Natural Science Foundation of China(30270321).
  • Received Date: 2003-07-08
  • In order to obtain that more information on the secondary and active site structure of polyphenol oxidase from nicotinan tobacco,FT-IR,synchronous fluorescence and Vis-UV have bee employed to study the secondary structure changes of polyphenol oxidase induced by pH. The results show that,compared with native PPO(pH=7),PPO at pH=2 contains less both a-helix and anti-parallel β-sheet,more random coil,and almost the same amount of β-turn,and that PPO at pH = 11 contains less a-helix,anti-parallel β-sheet,β-turn,and more random coil. The microenvironments of both Trp and Tyr residues in PPO undergo some changes with pH changing. With the decrease in pH values at the range of pH=7.0-3.38,the coordination between Cu2+ in the active site and imidazoles of histidine are strenghtened. Different LMCT bands of the PPO active site have been observed by changing pH,which result from the structure of Cu(Ⅱ)-imidazole and Cu(Ⅱ)-imidazolate.
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    沈阳化工大学材料科学与工程学院 沈阳 110142

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Spectroscopic Studies on pH-induced Changes in Secondary Structure of Pophenol Oxidase from Tobacco

doi: 10.1088/1674-0068/17/2/196-170
Funds:  Project supported by the National Natural Science Foundation of China(30270321).

Abstract: In order to obtain that more information on the secondary and active site structure of polyphenol oxidase from nicotinan tobacco,FT-IR,synchronous fluorescence and Vis-UV have bee employed to study the secondary structure changes of polyphenol oxidase induced by pH. The results show that,compared with native PPO(pH=7),PPO at pH=2 contains less both a-helix and anti-parallel β-sheet,more random coil,and almost the same amount of β-turn,and that PPO at pH = 11 contains less a-helix,anti-parallel β-sheet,β-turn,and more random coil. The microenvironments of both Trp and Tyr residues in PPO undergo some changes with pH changing. With the decrease in pH values at the range of pH=7.0-3.38,the coordination between Cu2+ in the active site and imidazoles of histidine are strenghtened. Different LMCT bands of the PPO active site have been observed by changing pH,which result from the structure of Cu(Ⅱ)-imidazole and Cu(Ⅱ)-imidazolate.

Xiao Hourong, Xu Xiaolong, Xie Yongshu, Sheng Liangquan, Zhang Yange, Liu Qingliang. Spectroscopic Studies on pH-induced Changes in Secondary Structure of Pophenol Oxidase from Tobacco[J]. Chinese Journal of Chemical Physics , 2004, 17(2): 196-170. doi: 10.1088/1674-0068/17/2/196-170
Citation: Xiao Hourong, Xu Xiaolong, Xie Yongshu, Sheng Liangquan, Zhang Yange, Liu Qingliang. Spectroscopic Studies on pH-induced Changes in Secondary Structure of Pophenol Oxidase from Tobacco[J]. Chinese Journal of Chemical Physics , 2004, 17(2): 196-170. doi: 10.1088/1674-0068/17/2/196-170

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