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Simultaneous multicolor fluorescence cross-correlation spectroscopy to detect higher order molecular interactions
Ling Chin Hwang1, Michael Gösch, Theo Lasser
1National University of Singapore, Department of Chemistry, Singapore 117543, Singapore.
Biophysical Journal
|April 25, 2006
Summary
Single wavelength excitation fluorescence cross-correlation spectroscopy (SW-FCCS) enables simultaneous excitation and detection of three fluorophores. This method accurately determines molecular interaction patterns and binding affinities, advancing studies in solution and living cells.
Area of Science:
- Biophysics
- Molecular Biology
- Analytical Chemistry
Background:
- Fluorescence cross-correlation spectroscopy (FCCS) is vital for studying molecular interactions and dynamics.
- Traditional FCCS requires dual-color detection systems, often using superimposed laser beams or two-photon excitation.
- Single wavelength excitation fluorescence cross-correlation spectroscopy (SW-FCCS) has emerged for spectrally similar fluorophores.
Purpose of the Study:
- To demonstrate SW-FCCS for simultaneous excitation and detection of up to three fluorophores.
- To develop a theoretical model for triple pairwise cross-correlations, accounting for crosstalk and quenching.
- To validate SW-FCCS for analyzing complex molecular interactions using a ligand-receptor model.
Main Methods:
- Simultaneous excitation of three spectrally distinct fluorophores using a single laser wavelength.
- Detection of cross-correlation signals in three separate channels.
- Application of a theoretical model for triple pairwise cross-correlations and analysis of binding events.
- Experimental validation using a biotin-streptavidin system with differentially labeled components.
Main Results:
- SW-FCCS successfully achieved simultaneous excitation and detection of three fluorophores.
- The developed model accurately described triple pairwise cross-correlations, including crosstalk effects.
- Experimental data confirmed SW-FCCS's ability to detect binding of three interacting partners.
- Cross-correlation amplitudes correlated with stoichiometric binding, allowing determination of dissociation constants.
Conclusions:
- SW-FCCS is a powerful extension of FCCS, enabling multi-component interaction analysis.
- The method allows for precise determination of molecular interaction patterns and binding affinities.
- SW-FCCS offers a simplified yet effective approach for studying complex molecular systems in various environments.