Title
Hydrogen-Bond Driven Loop-Closure Kinetics In Unfolded Polypeptide Chains
Abstract
Characterization of the length dependence of end-to-end loop-closure kinetics in unfolded polypeptide chains provides an understanding of early steps in protein folding. Here, loop-closure in poly-glycine-serine peptides is investigated by combining single-molecule fluorescence spectroscopy with molecular dynamics simulation. For chains containing more than 10 peptide bonds loop-closing rate constants on the 20-100 nanosecond time range exhibit a power-law length dependence. However, this scaling breaks down for shorter peptides, which exhibit slower kinetics arising from a perturbation induced by the dye reporter system used in the experimental setup. The loop-closure kinetics in the longer peptides is found to be determined by the formation of intra-peptide hydrogen bonds and transient beta-sheet structure, that accelerate the search for contacts among residues distant in sequence relative to the case of a polypeptide chain in which hydrogen bonds cannot form. Hydrogen-bond-driven polypeptide-chain collapse in unfolded peptides under physiological conditions found here is not only consistent with hierarchical models of protein folding, that highlights the importance of secondary structure formation early in the folding process, but is also shown to speed up the search for productive folding events.
Year
DOI
Venue
2010
10.1371/journal.pcbi.1000645
PLOS COMPUTATIONAL BIOLOGY
Keywords
Field
DocType
protein folding,kinetics,fluorescence spectroscopy,hydrogen bonding,molecular dynamics simulation,hydrogen bond,secondary structure,rate constant,hierarchical model,power law
Reaction rate constant,Protein folding,Biology,Biophysics,Fluorescence spectroscopy,Molecular dynamics,Peptide bond,Hydrogen bond,Genetics,Kinetics,Protein secondary structure
Journal
Volume
Issue
ISSN
6
1
1553-7358
Citations 
PageRank 
References 
2
0.47
1
Authors
5
Name
Order
Citations
PageRank
Isabella Daidone151.53
Hannes Neuweiler220.47
Sören Doose320.47
Markus Sauer461.20
Jeremy C. Smith517027.74