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Impact of ion binding on poly-l-lysine (un)folding energy landscape and kinetics

Xiong, K and Asher, SA (2012) Impact of ion binding on poly-l-lysine (un)folding energy landscape and kinetics. Journal of Physical Chemistry B, 116 (24). 7102 - 7112. ISSN 1520-6106

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We utilize T-jump UV resonance Raman spectroscopy (UVRR) to study the impact of ion binding on the equilibrium energy landscape and on (un)folding kinetics of poly-l-lysine (PLL). We observe that the relaxation rates of the folded conformations (including π-helix (bulge), pure α-helix, and turns) of PLL are slower than those of short alanine-based peptides. The PLL pure α-helix folding time is similar to that of short alanine-based peptides. We for the first time have directly observed that turn conformations are α-helix and π-helix (bulge) unfolding intermediates. ClO 4- binding to the Lys side chain -NH3+ groups and the peptide backbone slows the α-helix unfolding rate compared to that in pure water, but little impacts the folding rate, resulting in an increased α-helix stability. ClO4- binding significantly increases the PLL unfolding activation barrier but little impacts the folding barrier. Thus, the PLL folding coordinate(s) differs from the unfolding coordinate(s). The-π helix (bulge) unfolding and folding coordinates do not directly go through the α-helix energy well. Our results clearly demonstrate that PLL (un)folding is not a two-state process. © 2012 American Chemical Society.


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Item Type: Article
Status: Published
CreatorsEmailPitt UsernameORCID
Xiong, K
Asher, SAasher@pitt.eduASHER
Date: 21 June 2012
Date Type: Publication
Journal or Publication Title: Journal of Physical Chemistry B
Volume: 116
Number: 24
Page Range: 7102 - 7112
DOI or Unique Handle: 10.1021/jp302007g
Schools and Programs: Dietrich School of Arts and Sciences > Chemistry
Refereed: Yes
ISSN: 1520-6106
MeSH Headings: Ions--chemistry; Kinetics; Perchloric Acid--chemistry; Polylysine--chemistry; Polylysine--metabolism; Protein Folding; Protein Structure, Secondary; Sodium Compounds--chemistry; Spectrum Analysis, Raman; Water--chemistry
Other ID: NLM NIHMS380037, NLM PMC3381074
PubMed Central ID: PMC3381074
PubMed ID: 22612556
Date Deposited: 08 Feb 2013 20:47
Last Modified: 22 Jun 2021 13:55


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