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Study of the aggregation mechanism of polyglutamine peptides using replica exchange molecular dynamics simulations.
MedLine Citation:
PMID:  23288093     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Polyglutamine (polyQ, a peptide) with an abnormal repeat length is the causative agent of polyQ diseases, such as Huntington's disease. Although glutamine is a polar residue, polyQ peptides form insoluble aggregates in water, and the mechanism for this aggregation is still unclear. To elucidate the detailed mechanism for the nucleation and aggregation of polyQ peptides, replica exchange molecular dynamics simulations were performed for monomers and dimers of polyQ peptides with several chain lengths. Furthermore, to determine how the aggregation mechanism of polyQ differs from those of other peptides, we compared the results for polyQ with those of polyasparagine and polyleucine. The energy barrier between the monomeric and dimeric states of polyQ was found to be relatively low, and it was observed that polyQ dimers strongly favor the formation of antiparallel β-sheet structures. We also found a characteristic behavior of the monomeric polyQ peptide: a turn at the eighth residue is always present, even when the chain length is varied. We previously showed that a structure including more than two sets of β-turns is stable, so a long monomeric polyQ chain can act as an aggregation nucleus by forming several pairs of antiparallel β-sheet structures within a single chain. Since the aggregation of polyQ peptides has some features in common with an amyloid fibril, our results shed light on the mechanism for the aggregation of polyQ peptides as well as the mechanism for the formation of general amyloid fibrils, which cause the onset of amyloid diseases.
Authors:
Miki Nakano; Kuniyoshi Ebina; Shigenori Tanaka
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-1-5
Journal Detail:
Title:  Journal of molecular modeling     Volume:  -     ISSN:  0948-5023     ISO Abbreviation:  J Mol Model     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-1-4     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9806569     Medline TA:  J Mol Model     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Graduate School of Human Development and Environment, Kobe University, 3-11, Tsurukabuto, Nada, Kobe, 657-8501, Japan, nakano@eniac.scitec.kobe-u.ac.jp.
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