Fluorescence-quenching-resolved spectroscopy of proteins

Area of Science:

• Biochemistry
• Biophysics
• Spectroscopy

Background:

• Protein fluorescence emission spectra provide insights into structure and dynamics.
• Resolving spectra from multiple tryptophan residues is challenging due to spectral overlap.
• Existing methods for spectral deconvolution can be complex or require specialized equipment.

Purpose of the Study:

• To develop a novel, accessible method for resolving protein fluorescence emission spectra.
• To differentiate spectral contributions from individual tryptophan residues based on quencher accessibility.
• To validate the new method using well-characterized proteins.

Main Methods:

• Utilizing fluorescence-quenching data from tryptophan residues.
• Applying the Stern-Volmer quenching model at specific emission wavelengths.
• Employing iterative non-linear least-squares fitting to decompose steady-state spectra.
• Using selective quenchers to differentiate fluorophore accessibility.

Main Results:

• Successfully resolved fluorescence emission spectra into components attributed to individual tryptophan residues.
• Characterized tryptophan residue accessibility to quenchers.
• Demonstrated excellent agreement with results from single-photon counting and phase methods for alcohol dehydrogenase and metalloprotease.
• Validated the method's applicability to proteins with multiple tryptophan residues.

Conclusions:

• The described fluorescence-quenching method effectively resolves protein emission spectra.
• This technique provides a simple, cost-effective alternative for analyzing tryptophan fluorescence.
• The method allows for characterization of tryptophan residue environments within proteins.