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Issue 6, 2014
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A dual emission fluorescent probe enables simultaneous detection of glutathione and cysteine/homocysteine

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Abstract

Many studies have shown that glutathione (GSH) and cysteine (Cys)/homocysteine (Hcy) levels are interrelated in biological systems. To unravel the complicated biomedical mechanisms by which GSH and Cys/Hcy are involved in various disease states, probes that display distinct signals in response to GSH and Cys/Hcy are highly desirable. In this work, we report a rhodol thioester (1) that responds to GSH and Cys/Hcy with distinct fluorescence emissions in neutral media. Probe 1 reacts with Cys/Hcy to form the corresponding deconjugated spirolactam via a tandem native chemical ligation (NCL) reaction. This intramolecular spirocyclization leads to the “quinone–phenol” transduction of rhodol dyes, and an excited-state intramolecular proton transfer (ESIPT) process between the phenolic hydroxyl proton and the aromatic nitrogen in the benzothiazole unit occurs upon photoexcitation, thus affording 2-(2′-hydroxyphenyl) benzothiazole (HBT) emission (454 nm). In the case of the tripeptide GSH, only transthioesterification takes place removing the intramolecular photo-induced electron transfer (PET) process caused by the electron deficient 4-nitrobenzene moiety giving rise to a large fluorescence enhancement at the rhodol emission band (587 nm). The simultaneous detection of GSH and Cys/Hcy is attributed to the significantly different rates of intramolecular S,N-acyl shift of their corresponding thioester adducts derived from 1. The utility of probe 1 has been demonstrated in various biological systems including serum and cells.

Graphical abstract: A dual emission fluorescent probe enables simultaneous detection of glutathione and cysteine/homocysteine

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Publication details

The article was received on 28 Jan 2014, accepted on 25 Feb 2014 and first published on 26 Feb 2014


Article type: Edge Article
DOI: 10.1039/C4SC00308J
Citation: Chem. Sci., 2014,5, 2177-2183

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    A dual emission fluorescent probe enables simultaneous detection of glutathione and cysteine/homocysteine

    X. Yang, Q. Huang, Y. Zhong, Z. Li, H. Li, M. Lowry, J. O. Escobedo and R. M. Strongin, Chem. Sci., 2014, 5, 2177
    DOI: 10.1039/C4SC00308J

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