A 'turn-on' FRET peptide sensor based on the mercury binding protein MerP.

Area of Science:

• Biochemistry
• Analytical Chemistry
• Biotechnology

Background:

• Development of sensitive and selective chemosensors for metal ion detection is crucial in environmental monitoring and biological studies.
• Fluorescence resonance energy transfer (FRET) based sensors offer high sensitivity and selectivity.
• The mercury-binding protein MerP provides a unique metal-binding motif.

Purpose of the Study:

• To synthesize and characterize a novel fluorescent peptidyl chemosensor based on the MerP protein.
• To investigate the FRET capabilities of the sensor for metal ion detection.
• To evaluate the sensor's sensitivity and selectivity for Hg(2+) and other metal ions.

Main Methods:

• Solid-phase peptide synthesis using Fmoc chemistry to construct the peptidyl sensor.
• Incorporation of tryptophan (donor) and dansyl (acceptor) fluorophores flanking the MerP metal-binding loop.
• Fluorescence spectroscopy to monitor FRET response upon metal ion binding in aqueous solution at pH 7.0.

Main Results:

• The synthesized sensor exhibited a 'turn-on' FRET response for Hg(2+), Zn(2+), Cd(2+), and Ag(+).
• Detection limits were determined for Hg(2+) (280 μg L(-1)), Zn(2+) (6 μg L(-1)), Cd(2+) (103 μg L(-1)), and Ag(+) (496 μg L(-1)).
• The observed fluorescence enhancement for Hg(2+) is unique, as mercury typically quenches fluorescence, indicating a more sensitive detection mechanism.

Conclusions:

• A novel FRET-based peptidyl chemosensor derived from MerP protein was successfully synthesized.
• The sensor demonstrates sensitive and selective detection of Hg(2+), Zn(2+), Cd(2+), and Ag(+) via a 'turn-on' fluorescence mechanism.
• This sensor design offers enhanced sensitivity compared to traditional fluorescence quenching-based sensors, particularly for Hg(2+).