Anticooperative Nearest-Neighbor Interactions between Residues in Unfolded Peptides and Proteins

Reinhard Schweitzer-Stenner; Siobhan E Toal

doi:10.1016/j.bpj.2018.01.022

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Anticooperative Nearest-Neighbor Interactions between Residues in Unfolded Peptides and Proteins

Journal article

Open access

Peer reviewed

Anticooperative Nearest-Neighbor Interactions between Residues in Unfolded Peptides and Proteins

Reinhard Schweitzer-Stenner and Siobhan E Toal

Biophysical journal, v 114(5), pp 1046-1057

13 Mar 2018

DOI: https://doi.org/10.1016/j.bpj.2018.01.022

PMID: 29539392

Featured in Collection : UN Sustainable Development Goals @ Drexel

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Abstract

Intrinsically Disordered Proteins - chemistry

Oligopeptides - chemistry

Peptides - chemistry

Protein Conformation, beta-Strand

Protein Unfolding

Temperature

Growing evidence suggests that the conformational distributions of amino acid residues in unfolded peptides and proteins depend on the nature of the nearest neighbors. To explore whether the underlying interactions would lead to a breakdown of the isolated pair hypothesis of the classical random coil model, we further analyzed the conformational propensities that were recently obtained for the two guest residues (x,y) of GxyG tetrapeptides. We constructed a statistical thermodynamics model that allows for cooperative as well as for anticooperative interactions between adjacent residues adopting either a polyproline II or a β-strand conformation. Our analysis reveals that the nearest-neighbor interactions between most of the central residues in the investigated GxyG peptides are anticooperative. Interaction Gibbs energies are rather large at high temperatures (350 K), at which point many proteins undergo thermal unfolding. At room temperature, these interaction energies are less pronounced. We used the obtained interaction parameter in a Zimm-Bragg/Ising-type approach to calculate the temperature dependence of the ultraviolet circular dichroism (CD) of the MAX3 peptide, which is predominantly built by KV repeats. The agreement between simulation and experimental data was found to be satisfactory. Finally, we analyzed the temperature dependence of the CD and J(H H ) parameters of the amyloid β fragment. The results of this analysis and a more qualitative consideration of the temperature dependence of denatured proteins probed by CD spectroscopy further corroborate the dominance of anticooperative nearest-neighbor interactions. Generally, our results show that unfolded peptides-and most likely also proteins-exhibit some similarity with antiferromagnetic systems.

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Details

Title: Anticooperative Nearest-Neighbor Interactions between Residues in Unfolded Peptides and Proteins
Creators: Reinhard Schweitzer-Stenner - Drexel University
Siobhan E Toal - University of Pennsylvania
Publication Details: Biophysical journal, v 114(5), pp 1046-1057
Publisher: Elsevier
Resource Type: Journal article
Language: English
Academic Unit: [Retired Faculty]; Chemistry
Web of Science ID: WOS:000428017500009
Scopus ID: 2-s2.0-85043528250
Other Identifier: 991019167723304721

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Collaboration types: Domestic collaboration
Web of Science research areas: Biophysics