A Photoprotective Effect by Cation-π-Interaction? Quenching of Singlet Oxygen by an Indole Cation-π Model System.
A Photoprotective Effect by Cation-π-Interaction? Quenching of Singlet Oxygen by an Indole Cation-π Model System.
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DOI：
10.1111/php.13287
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发表时间：
2020-11
影响因子：
3.3
通讯作者：
Selke M
中科院分区：
文献类型：
--
作者：
Arevalo GE;Cagan DA;Monsour CG;Garcia AC;McCurdy A;Selke M
我们研究了阳离子-π相互作用对色氨酸模型体系与单线态氧相互作用（即II型光氧化）敏感性的影响。该模型系统由两个吲哚单元连接到一个lynyl冠醚，以测量在钠阳离子的存在下（即吲哚单元受到阳离子-π相互作用）和在没有这种相互作用的情况下，由吲哚单元去除单线态氧的总速率。我们发现，阳离子-π相互作用显著降低了模型系统中单线态氧的总去除速率（kT），即在没有钠阳离子的情况下为（kT = 2.4±0.2）×108 M− 1 sec −1，而在钠阳离子与冠醚络合时为（kT = 6.9±0.7）×107 M− 1 sec −1。此外，我们发现吲哚部分进行I型光氧化过程与三重激发亚甲蓝，这种效果也被抑制的阳离子-π相互作用。吲哚基团与单线态氧的化学反应速率也较慢，在我们的模型系统中的钠阳离子络合后，虽然我们无法获得一个确切的比例，由于两个吲哚部分的化学反应速率的差异。在吲哚-冠醚模型体系中，钠阳离子与吲哚基团之间的阳离子-π相互作用显著降低了单线态氧的总去除速率（kT）.吲哚基团的I型光氧化也被阳离子-π相互作用抑制。这些结果暗示色氨酸可能通过阳离子-π相互作用而具有光保护作用。
We investigated the effect of the cation-π interaction on the susceptibility of a tryptophan model system towards interaction with singlet oxygen, i.e. Type II photooxidation. The model system consists of two indole units linked to a lariat crown ether to measure the total rate of removal of singlet oxygen by the indole units in the presence of sodium cations (i.e. indole units subject to a cation-π interaction) and in the absence of this interaction. We found that the cation-π interaction significantly decreases the total rate of removal of singlet oxygen (kT) for the model system, i.e. (kT = 2.4±0.2)×108 M−1sec−1 without sodium cation vs. (kT = 6.9±0.7)×107 M−1sec−1 upon complexation of sodium cation to the crown ether. Furthermore, we found that the indole moieties undergo Type I photooxidation processes with triplet excited Methylene Blue; this effect is also inhibited by the cation-π interaction. The chemical rate of reaction of the indole groups with singlet oxygen is also slower upon complexation of sodium cation in our model system, although we were unable to obtain an exact ratio due to differences of the chemical reaction rates of the two indole moieties. The cation-π interaction between a sodium cation and an indole moiety significantly decreases the total rate of removal of singlet oxygen (kT) in an indole-crown model system. A Type I photooxidation of the indole group is also inhibited by the cation-π interaction. These results imply that there may be a photoprotective effect by the cation-π interaction for tryptophan.
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影响因子：
15
作者：
Jensen, Rasmus Lybech;Arnbjerg, Jacob;Ogilby, Peter R.
通讯作者：
Ogilby, Peter R.
影响因子：
15
作者：
Cagan, David A.;Garcia, Arman C.;Selke, Matthias
通讯作者：
Selke, Matthias
影响因子：
3.9
作者：
Mahanta, Sanjeev Pran;Dutta, Biswajyoti;Bania, Kusum K.
通讯作者：
Bania, Kusum K.
影响因子：
3.3
作者：
MICHAELI, A;FEITELSON, J
通讯作者：
FEITELSON, J
影响因子：
3.1
作者：
Ronsein, Graziella Eliza;Bof de Oliveira, Mauricio Cesar;Di Mascio, Paolo
通讯作者：
Di Mascio, Paolo