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A specific fluorescent probe reveals compromised activity of methionine sulfoxide reductases in Parkinson's disease † † Electronic supplementary information (ESI) available: The characterization of probes, experimental procedures, supporting data and original spectra ( 1 H NMR, 13 C NMR, and MS) of the final 23 compounds. See DOI: 10.1039/c6sc04708d Click here for additional data file.

View Article: PubMed Central - PubMed

ABSTRACT

Oxidation of methionine residues to methionine sulfoxide (MetSO) may cause changes in protein structure and function, and may eventually lead to cell damage. Methionine sulfoxide reductases (Msrs) are the only known enzymes that catalyze the reduction of MetSO back to methionine by taking reducing equivalents from the thioredoxin system, and thus protect cells from oxidative damage. Nonetheless, a lack of convenient assays for the enzymes hampers the exploration of their functions. We report the discovery of Msr-blue, the first turn-on fluorescent probe for Msr with a >100-fold fluorescence increment from screening a rationally-designed small library. Intensive studies demonstrated the specific reduction of Msr-blue by the enzymes. Msr-blue is ready to determine Msr activity in biological samples and live cells. Importantly, we disclosed a decline of Msr activity in a Parkinson's model, thus providing a mechanistic linkage between the loss of function of Msrs and the development of neurodegeneration. The strategy for the discovery of Msr-blue would also provide guidance for developing novel probes with longer excitation/emission wavelengths and specific probes for Msr isoforms.

No MeSH data available.


Design of potential probes for Msrs.
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sch1: Design of potential probes for Msrs.

Mentions: Developing specific probes for a particular biomolecule is of great importance to unveil its function in physiological/pathophysiological processes. Among various detection techniques, fluorescence-based assays are widely adopted due to their high sensitivity, operational simplicity, and super biocompatibility. Therefore, the past years have witnessed an increase in the number of studies that focus on developing diverse fluorescent probes for studying various protein activities16–27 as well as small biomolecule functions.28–35 One of the outstanding and well-recognized strategies in designing fluorescent probes is the manipulation of the intramolecular charge transfer (ICT) process, as the alteration of such a process is usually accompanied with a pronounced change in the absorbance/fluorescence profiles of a molecule, which forms the basis of the fluorescence sensing. Manipulation of the ICT process could be easily achieved by tuning the electronic character of the substituents attached to a fluorophore by exchanging electron donating groups with electron withdrawing groups or vice versa.36,37 The reaction that is catalyzed by Msr converts sulfoxides to the corresponding sulfides, which enables the transformation of an electron withdrawing group to an electron donating group. Taking into consideration the broad substrate scope of Msrs, we thus hypothesized that attachment of the methyl sulfoxide moiety to certain fluorophores might generate turn-on probes for the enzymes (Scheme 1).


A specific fluorescent probe reveals compromised activity of methionine sulfoxide reductases in Parkinson's disease † † Electronic supplementary information (ESI) available: The characterization of probes, experimental procedures, supporting data and original spectra ( 1 H NMR, 13 C NMR, and MS) of the final 23 compounds. See DOI: 10.1039/c6sc04708d Click here for additional data file.
Design of potential probes for Msrs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382841&req=5

sch1: Design of potential probes for Msrs.
Mentions: Developing specific probes for a particular biomolecule is of great importance to unveil its function in physiological/pathophysiological processes. Among various detection techniques, fluorescence-based assays are widely adopted due to their high sensitivity, operational simplicity, and super biocompatibility. Therefore, the past years have witnessed an increase in the number of studies that focus on developing diverse fluorescent probes for studying various protein activities16–27 as well as small biomolecule functions.28–35 One of the outstanding and well-recognized strategies in designing fluorescent probes is the manipulation of the intramolecular charge transfer (ICT) process, as the alteration of such a process is usually accompanied with a pronounced change in the absorbance/fluorescence profiles of a molecule, which forms the basis of the fluorescence sensing. Manipulation of the ICT process could be easily achieved by tuning the electronic character of the substituents attached to a fluorophore by exchanging electron donating groups with electron withdrawing groups or vice versa.36,37 The reaction that is catalyzed by Msr converts sulfoxides to the corresponding sulfides, which enables the transformation of an electron withdrawing group to an electron donating group. Taking into consideration the broad substrate scope of Msrs, we thus hypothesized that attachment of the methyl sulfoxide moiety to certain fluorophores might generate turn-on probes for the enzymes (Scheme 1).

View Article: PubMed Central - PubMed

ABSTRACT

Oxidation of methionine residues to methionine sulfoxide (MetSO) may cause changes in protein structure and function, and may eventually lead to cell damage. Methionine sulfoxide reductases (Msrs) are the only known enzymes that catalyze the reduction of MetSO back to methionine by taking reducing equivalents from the thioredoxin system, and thus protect cells from oxidative damage. Nonetheless, a lack of convenient assays for the enzymes hampers the exploration of their functions. We report the discovery of Msr-blue, the first turn-on fluorescent probe for Msr with a >100-fold fluorescence increment from screening a rationally-designed small library. Intensive studies demonstrated the specific reduction of Msr-blue by the enzymes. Msr-blue is ready to determine Msr activity in biological samples and live cells. Importantly, we disclosed a decline of Msr activity in a Parkinson's model, thus providing a mechanistic linkage between the loss of function of Msrs and the development of neurodegeneration. The strategy for the discovery of Msr-blue would also provide guidance for developing novel probes with longer excitation/emission wavelengths and specific probes for Msr isoforms.

No MeSH data available.