The treatment of electrostatic interactions in molecular simulations is of fundamental importance. Ewald and related methods are being increasingly used to the detriment of cutoff schemes, which are known to produce several artifacts. A potential drawback of the Ewald method is the spatial periodicity that is imposed to the system, which could produce artifacts when applied in the simulation of liquids. In this work we analyze the octaalanine peptide with charged termini in explicit solvent, for which severe effects due to the use of Ewald sums were predicted using continuum electrostatics. Molecular Dynamics simulations for a total of 158 nanoseconds were performed in cells of different sizes. From the comparison of the results of different system sizes, no significant periodicity-induced artifacts were observed. It is argued that in current biomolecular simulations, the incomplete sampling is likely to affect the results to a larger extent than the artifacts induced by the use of Ewald sums.
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http://dx.doi.org/10.1080/07391102.2005.10507054 | DOI Listing |
Biophys Chem
October 2019
Adam Mickiewicz University in Poznań, Faculty of Chemistry, Umultowska 89b, 61-614 Poznań, Poland. Electronic address:
Peptides can aggregate into ordered structures with different morphologies. The aggregation mechanism and evolving structures are the subject of intense research. In this paper we have used molecular dynamics to examine the sequence-dependence of aggregation kinetics for three short peptides: octaalanine (Ala8), octaasparagine (Asn8), and the heptapeptide GNNQQNY (abbreviated as GNN).
View Article and Find Full Text PDFJ Biomol Struct Dyn
July 2017
a Department of Chemistry , Indian Institute of Technology Bombay, Mumbai 400076 , India.
Protein folding remains an unsolved problem as main-chain, side-chain, and solvent interactions remain entangled and have been hard to resolve. Polyalanines are promising models to analyze protein folding initiation and propagation structurally as well as energetically. In the present work, the effect of chain-length and N-terminal residue stereochemistry in polyalanine peptides are investigated for their role in the nucleation of α-helical conformation.
View Article and Find Full Text PDFJ Chem Theory Comput
February 2016
Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians Universität München, Oettingenstrasse 67, 80538 München, Germany.
Continuous tempering molecular dynamics (CTMD) generalizes simulated tempering (ST) to a continuous temperature space. Opposed to ST the CTMD equations of motion are fully deterministic and feature a conserved quantity that can be used to validate the simulation. Three variants of CTMD are discussed and compared by means of a simple test system.
View Article and Find Full Text PDFJ Phys Chem B
May 2006
School of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India.
In search of the link between sequence and conformation in protein structures, we perform molecular dynamics analysis of the effect of stereochemical mutation in end-protected octa-alanine Ac-Ala8-NHMe from poly-L to an alternating-L,D structure. The mutation has a dramatic effect, transforming the peptide from a condition of extreme sensitivity to one of extreme insensitivity to solvent. Examining the molecular folds of poly-L and alternating-L,D structure in atomistic detail, we find them to differ in the relationship between peptide dipolar interactions at the local and nonlocal levels, either conflicting or harmonious depending upon the chain stereochemistry.
View Article and Find Full Text PDFJ Biomol Struct Dyn
October 2005
Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, CIQUIBIC (CONICET), Pabellón Argentina, Ciudad Universitaria, CP 5000 Córdoba, Argentina.
The treatment of electrostatic interactions in molecular simulations is of fundamental importance. Ewald and related methods are being increasingly used to the detriment of cutoff schemes, which are known to produce several artifacts. A potential drawback of the Ewald method is the spatial periodicity that is imposed to the system, which could produce artifacts when applied in the simulation of liquids.
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