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Distance mapping in proteins using fluorescence spectroscopy: the tryptophan-induced quenching (TrIQ) method
Steven E Mansoor1, Mark A Dewitt, David L Farrens
1Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239-3098, United States.
Biochemistry
|October 5, 2010
Summary
We developed tryptophan-induced quenching (TrIQ), a sensitive method to measure protein conformational dynamics and interactions. TrIQ maps short-range distances (5-15 Å) within proteins using fluorescence spectroscopy.
Area of Science:
- Biophysics
- Structural Biology
- Biochemistry
Background:
- Studying protein structure-function relationships is challenging.
- Real-time measurement of protein structural changes is lacking.
Purpose of the Study:
- To improve and present tryptophan-induced quenching (TrIQ) as a method for studying protein dynamics.
- To analyze the TrIQ effect on various fluorophores and protein structures.
Main Methods:
- Developed and applied tryptophan-induced quenching (TrIQ) spectroscopy.
- Measured TrIQ effect of tryptophan on five different fluorophores attached to T4 lysozyme.
- Analyzed distance dependence and quenching profiles.
Main Results:
- TrIQ is a sensitive, inexpensive method for short-range (5-15 Å) distance measurements.
- The extent of TrIQ is distance-dependent, especially for smaller probes.
- Each fluorophore exhibits a unique TrIQ "sphere of quenching" influenced by size, flexibility, and linker length.
Conclusions:
- TrIQ provides a complementary approach to FRET for studying protein structure.
- TrIQ enables precise mapping of distances and monitoring of conformational changes.
- The "sphere of quenching" offers insights into Trp-probe interactions and protein dynamics.
