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Looking for the peptide 2.0(5) -helix: A solvent- and main-chain length-dependent conformational switch probed by electron transfer across c(α,α) -diethylglycine homo-oligomers.
MedLine Citation:
PMID:  23335167     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
The elusive, multiple fully extended (2.0(5) -helix) peptide conformation was searched with a series of C(α,α) -diethylglycine homo-oligomers (n = 1 to 5) functionalized by an electron transfer (ET) donor···acceptor (D···A) pair in acetonitrile and chloroform solutions. In the former solvent, all peptides investigated were shown to populate the 3(10) -helix conformation, whereas in chloroform the two shortest members of the series (n = 1 and n = 2) adopt predominantly the 2.0(5) -helix. Interestingly, for the longest components (n = 3 to n = 5) in this latter solvent, an equilibrium between the 2.0(5) - and 3(10) -helices takes place, the latter conformation becoming progressively more populated as the peptide main-chain length increases. Time-resolved fluorescence (TRF) experiments and molecular mechanics (MM) calculations were used in a combined approach to analyze the ET efficiencies and to associate a specific conformer (from MM) to an experimentally determined ET rate constant (from TRF). Therefore, because of the high sensitivity of the ET process to the D···A distance, ET can be used as a kinetic spectroscopic ruler, allowing for the characterization of the transition from a pure 3(10) -helix conformation to a 2.0(5) -/3(10) -helix equilibrium for the longest Deg homo-peptides of this series upon changing the solvent from acetonitrile to chloroform. To our knowledge, this is the first time that the electronic coupling factor β for ET across a peptide chain in the 2.0(5) -helix conformation is provided. © 2012 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 100: 51-63, 2013.
Authors:
Raffaella Lettieri; Martina Bischetti; Emanuela Gatto; Antonio Palleschi; Elisabetta Ricci; Fernando Formaggio; Marco Crisma; Claudio Toniolo; Mariano Venanzi
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Biopolymers     Volume:  100     ISSN:  0006-3525     ISO Abbreviation:  Biopolymers     Publication Date:  2013 Apr 
Date Detail:
Created Date:  2013-01-21     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0372525     Medline TA:  Biopolymers     Country:  United States    
Other Details:
Languages:  eng     Pagination:  51-63     Citation Subset:  IM    
Copyright Information:
Copyright © 2012 Wiley Periodicals, Inc.
Affiliation:
Department of Chemical Sciences and Technologies, University of Rome 'Tor Vergata', 00133 Rome, Italy.
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