A Bifunctional Molecule as an Artificial Flavin Mononucleotide Cyclase and a Chemosensor for Selective Fluorescent Detection of Flavins

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• 作者：Hyun-Woo Rhee ; So Jung Choi ; Sang Ho Yoo ; Yong Oh Jang ; Hun Hee Park ; Rosa Mara Pinto ; Jos Carlos Cameselle ; Francisco J. Sandoval ; Sanja Roje ; Kyungja Han ; Doo Soo Chung ; Junghun Suh ; Jong-In Hong
• 刊名：Journal of the American Chemical Society
• 出版年：2009
• 出版时间：July 29, 2009
• 年：2009
• 卷：131
• 期：29
• 页码：10107-10112
• 全文大小：239K
• 年卷期：v.131,no.29(July 29, 2009)
• ISSN：1520-5126

文摘

Flavins, comprising flavin mononucleotide (FMN), flavin adenine dinucleotide (FAD), and riboflavin (RF, vitamin B₂), play important roles in numerous redox reactions such as those taking place in the electron-transfer chains of mitochondria in all eukaryotes and of plastids in plants. A selective chemosensor for flavins would be useful not only in the investigation of metabolic processes but also in the diagnosis of diseases related to flavins; such a sensor is presently unavailable. Herein, we report the first bifunctional chemosensor (PTZ-DPA) for flavins. PTZ-DPA consists of bis(Zn²⁺-dipicolylamine) and phenothiazine. Bis(Zn²⁺-dipicolylamine) (referred to here as XyDPA) was found to be an excellent catalyst in the conversion of FAD into cyclic FMN (riboflavin 4′,5′-cyclic phosphate, cFMN) under physiological conditions, even at pH 7.4 and 27 °C, with less than 1 mol % of substrate. Utilizing XyDPA’s superior function as an artificial FMN cyclase and phenothiazine as an electron donor able to quench the fluorescence of an isoalloxazine ring, PTZ-DPA enabled selective fluorescent discrimination of flavins (FMN, FAD, and RF): FAD shows ON(+), FMN shows OFF(−), and RF shows NO(0) fluorescence changes upon the addition of PTZ-DPA. With this selective sensing property, PTZ-DPA is applicable to real-time fluorescent monitoring of riboflavin kinase (RF to FMN), alkaline phosphatase (FMN to RF), and FAD synthetase (FMN to FAD).