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Updated: Jul 17, 2026
12:42
Microfluidic Mixers for Studying Protein Folding
Published on: April 10, 2012
Loop formation in unfolded polypeptide chains on the picoseconds to microseconds time scale.
Beat Fierz1, Helmut Satzger, Christopher Root
1Division of Biophysical Chemistry, Biozentrum der Universität Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
Summary
Unfolded proteins form loops through rapid, multi-timescale motions. This search for favorable interactions reveals similarities between unfolded and folded protein energy landscapes, accelerating contact discovery.
Area of Science:
- Biophysics
- Protein Folding Dynamics
Background:
- Intrachain loop formation is crucial for protein folding.
- Unfolded polypeptide chains explore conformations to find favorable interactions.
Purpose of the Study:
- To directly measure loop formation in unfolded polypeptide chains.
- To investigate the time scales and mechanisms of loop formation.
Main Methods:
- Utilized triplet-triplet energy transfer between xanthone and naphthylalanine.
- Employed femtosecond and nanosecond laser-flash experiments.
- Studied loop formation in polyserine, poly(glycine-serine), and polyproline chains.
Main Results:
- Observed loop formation processes on multiple time scales (picoseconds to microseconds).
- Identified fast (3 ps) equilibrium conformations, complex kinetics (50-500 ps) indicating local motions, and large-scale motions (10-100 ns).
- Found similarities between the free energy landscapes of unfolded and folded proteins.
Conclusions:
- The free energy landscape of unfolded polypeptide chains shares properties with native proteins.
- Local energy minima accelerate the conformational search for favorable intrachain contacts.
- Loop formation involves hierarchical motions across different time scales.
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