A general fluorescence-based coupled assay for S-adenosylmethionine-dependent methyltransferases

Area of Science:

• Biochemistry
• Enzyme Assays
• Fluorescence Spectroscopy

Background:

• S-adenosylmethionine-dependent methyltransferases are crucial enzymes involved in various biological processes.
• Existing assays for these enzymes often lack sensitivity or require complex procedures.
• A simple, sensitive, and broadly applicable assay is needed to study methyltransferase activity.

Purpose of the Study:

• To develop a novel fluorescence-based assay for detecting the activity of S-adenosylmethionine-dependent methyltransferases.
• To utilize a fluorescein-cystamine-methyl red (FL-S-S-MR) reporter molecule for thiol detection.
• To demonstrate the assay's sensitivity and generalizability using catechol-O-methyltransferase.

Main Methods:

• Development of a two-step coupled enzyme assay using the FL-S-S-MR reporter molecule.
• Exploitation of fluorescence resonance energy transfer (FRET) for signal generation.
• Activation of the assay by thiols produced during the enzymatic reaction, specifically homocysteine.

Main Results:

• The FL-S-S-MR reporter molecule exhibited thiol-dependent fluorescence dequenching.
• The assay successfully detected
• The assay demonstrated specificity for thiols, enabling detection of biologically relevant levels.

Conclusions:

• The developed fluorescence assay is simple, sensitive, and specific for detecting S-adenosylmethionine-dependent methyltransferase activity.
• The FL-S-S-MR reporter system is effective for quantifying thiol production in enzymatic reactions.
• This fluorescence reporter approach shows potential for broad applicability to various thiol-producing assays.