Excited State Photoreaction between the Indole Side Chain of Tryptophan and Halocompounds Generates New Fluorophores and Unique Modifications
Excited State Photoreaction between the Indole Side Chain of Tryptophan and Halocompounds Generates New Fluorophores and Unique Modifications
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DOI：
10.1111/php.12279
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发表时间：
2014-09-01
影响因子：
3.3
通讯作者：
Edwards, Robert A.
中科院分区：
文献类型：
--
作者：
Ladner, Carol L.;Khai Tran;Edwards, Robert A.
含吲哚化合物与氯仿等三氯化合物的光反应产生荧光红移的产物。在蛋白质中，该反应可用于蛋白质的荧光检测。通过吲哚与卤代化合物的光化学反应产生的产物的表征很少已经完成，但对于其他荧光团，蛋白质标记剂和生物活性吲哚衍生物的发展是至关重要的。在这里，我们的特点是异构体的形式在色氨酸和氯仿之间的光反应中使用H-1-NMR的色氨酸和甲基化的衍生物，以揭示所形成的两个主要产品的结果从修改在4-和6-碳位置的吲哚环。在位置6处的反应生成6-甲酰基色氨酸，并且在位置4处的反应生成亚胺，因为最初形成的甲酰基衍生物进一步与色氨酸胺基反应。还测定了色氨酸与其它三卤代和单卤代化合物光反应生成的光产物的光谱性质和产物分子量。色氨酸的吲哚环可以用来自卤代化合物的各种添加物修饰，包括通过亚甲基将标记物添加到吲哚环。这为使用这种光化学产生新的基于色氨酸的荧光团和蛋白质标记策略开辟了可能性。
Photoreaction of indole containing compounds with chloroform and other trichlorocompounds generates products with redshifted fluorescence. In proteins, this reaction can be used for the fluorescent detection of proteins. Little characterization of products generated through the photochemical reaction of indoles with halocompounds has been done, yet is fundamental for the development of other fluorophores, protein labeling agents, and bioactive indole derivatives. Here, we have characterized which isomers form in the photoreaction between tryptophan and chloroform using H-1-NMR of tryptophan and methylated derivatives to reveal that the two major products that are formed result from modification at the 4- and 6-carbon positions of the indole ring. Reaction at position 6 generates 6-formyl tryptophan and the reaction at position 4 generates an imine because the formyl derivative that is initially formed reacts further with the tryptophan amine group. The spectroscopic properties and product molecular weights of photoproducts formed from photoreaction of tryptophan with other trihalo and monohalocompounds are also determined. The indole ring of tryptophan can be modified with various additions from halocompounds, including the addition of labels to the indole ring via methylene groups. This opens possibilities for generating novel tryptophan based fluorophores and protein labeling strategies using this photochemistry.