Issue 48, 2023

Critical assessment of selenourea as an efficient small molecule fluorescence quenching probe to monitor protein dynamics

Abstract

Organoselenium compounds have recently been the experimentalists’ delight due to their broad applications in organic synthesis, medicinal chemistry, and materials science. Selenium atom replacement of the carbonyl oxygen of the urea moiety dramatically reduces the HOMO–LUMO gap and oxidation potential, which completely changes the physicochemical properties of selenocarbonyl compounds. To our surprise, the photophysics and utility of a simple molecule such as selenourea (SeU) have not been explored in detail, which persuaded us to investigate its role in excited state processes. The steady-state emission, temperature-dependent time-correlated single photon counting, and femtosecond fluorescence upconversion experimental results confirmed that SeU significantly enhances the fluorescence quenching through a photoinduced electron transfer (PET) mechanism with an ∼10 ps ultrafast intrinsic PET lifetime component which is mostly absent in thiourea (TU). A wide range of fluorophores, based on their different redox abilities and fluorescence lifetimes covering a broad spectral window (λex: 390–590 nm and λem: 490–690 nm), were chosen to validate the proof of the concept. It was extended to tetramethylrhodamine (TMR)-5-maleimide labeled lysozyme protein, where we observed significant fluorescence quenching in the presence of SeU. The present work emphasizes that the high quenching efficiency with an ultrafast PET process, reduced orbital energy gap, and higher negative free energy change of the electron transfer reaction are the representative characteristics of selenourea or selenoamides to enable them as potential surrogates of thioamides or oxoamides quenching probes to monitor protein conformational changes and dynamics.

Graphical abstract: Critical assessment of selenourea as an efficient small molecule fluorescence quenching probe to monitor protein dynamics

Supplementary files

Article information

Article type
Edge Article
Submitted
16 Ago 2023
Accepted
26 Sep 2023
First published
26 Sep 2023
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2023,14, 14200-14210

Critical assessment of selenourea as an efficient small molecule fluorescence quenching probe to monitor protein dynamics

S. Jena, K. D. Tulsiyan, R. R. Sahoo, S. Rout, A. K. Sahu and H. S. Biswal, Chem. Sci., 2023, 14, 14200 DOI: 10.1039/D3SC04287A

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