Protein Aggregation at Solid/liquid Interfaces: a Monte Carlo Study with Explicit and Implicit Solvent Effects
Protein Aggregation at Solid/liquid Interfaces: a Monte Carlo Study with Explicit and Implicit Solvent Effects

Author: Rehman Fazeem

Publisher:

Published: 2013

Total Pages: 185

ISBN-13:

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"Metropolis Monte Carlo (MC) simulations were performed with positively charged peptides in aqueous solution to study changes in peptide conformations at solid/liquid interface, and its effects on protein aggregation. Intermediate-resolution diblock model peptide, comprising of 10 units of ALA (non-polar) and LYS (polar) amino acid residues, was used for the simulations. In the first approach to modeling, solvent effects were considered explicitly. The explicit model was then used to study two peptide molecules, in helical structure, at solid/liquid interface. In order to increase the number of peptide molecules in the simulation box, with reduced computational cost, an implicit solvent model was developed with nonadditive hydrogen bonding and hydrophobic interaction potentials. The implicit model was used to simulate two peptides of helical structure at charged surfaces (to compare with the explicit model), and ten peptides of random coil structure with and without charged surfaces. The peptides were observed to always move towards the negatively charged surface and orient with residues of complimentary charge settling close to the surface, maximizing the electrostatic interactions. On reaching the surface, the peptides partially lose their secondary structure and clusters around the hydrophobic ends; this restructuring and dehydration of the peptides provides the entropic drive for adsorption and subsequent misfolding events. The 2- peptide-water-surface system in explicit model was also simulated with periodic switching of surface charge polarity, to induce a "shaking effect" in order to observe possible peptide configurational changes"--Abstract, page iii.

Computer Simulations of Aggregation of Proteins and Peptides
Computer Simulations of Aggregation of Proteins and Peptides

Author: Mai Suan Li

Publisher:

Published: 2022

Total Pages: 478

ISBN-13: 9781071615461

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This volume provides computational methods and reviews various aspects of computational studies of protein aggregation. Chapters discuss the relationship between protein misfolding and protein aggregation, methods of prediction of aggregation propensities of protein, peptides, protein structure, results of computer simulations of aggregation, and computational simulations focused on specific diseases such as Alzheimer’s, Parkinson’s, and preeclampsia. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Authoritative and cutting-edge, Computer Simulations of Aggregation of Proteins and Peptides aims to ensure successful results in the further study of this vital field.

Computational Methods for Protein Structure Prediction and Modeling
Computational Methods for Protein Structure Prediction and Modeling

Author: Ying Xu

Publisher: Springer Science & Business Media

Published: 2007-08-24

Total Pages: 408

ISBN-13: 0387683720

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Volume One of this two-volume sequence focuses on the basic characterization of known protein structures, and structure prediction from protein sequence information. Eleven chapters survey of the field, covering key topics in modeling, force fields, classification, computational methods, and structure prediction. Each chapter is a self contained review covering definition of the problem and historical perspective; mathematical formulation; computational methods and algorithms; performance results; existing software; strengths, pitfalls, challenges, and future research.

Computer Simulations of Protein Folding and Aggregation
Computer Simulations of Protein Folding and Aggregation

Author:

Publisher:

Published: 2004

Total Pages:

ISBN-13:

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Computer simulation is used to study the competition between protein folding and aggregation, especially the formation of ordered structures that are also known as amyloid fibrils. Employing simplified protein models, we simulate multi-protein systems at a greater level of detail than has previously been possible, probe the fundamental physics that govern protein folding and aggregation, and explore the energetic and structural characteristics of amorphous and fibrillar protein aggregates. We first tackle the aggregation problem by using a low-resolution model called the lattice HP model developed by Lau and Dill. Dynamic Monte Carlo simulations are conducted on a system of simple, two-dimensional lattice protein molecules. We investigate how changing the rate of chemical or thermal renaturation affects the folding and aggregation behavior of the model protein molecule by simulating three renaturation methods: infinitely slow cooling, slow but finite cooling, and quenching. We find that the infinitely slow cooling method provides the highest refolding yields. We then study how the variation of protein concentration affects the refolding yield by simulating the pulse renaturation method, in which denatured proteins are slowly added to the refolding simulation box in a stepwise manner. We observe that the pulse renaturation method provides refolding yields that are substantially higher than those observed in the other three methods even at high packing fractions. We then investigate the folding of a polyalanine peptide with the sequence Ac-KA14K-NH2 using a novel off-lattice, intermediate-resolution protein model originally developed by Smith and Hall. The thermodynamics of a system containing a single Ac-KA14K-NH2 molecule is explored by employing the replica exchange simulation method to map out the conformational transitions as a function of temperature. We also explore the influence of solvent type on the folding process by varying the relative strength of the sid.

Computational Methods to Study the Structure and Dynamics of Biomolecules and Biomolecular Processes
Computational Methods to Study the Structure and Dynamics of Biomolecules and Biomolecular Processes

Author: Adam Liwo

Publisher: Springer

Published: 2018-12-19

Total Pages: 851

ISBN-13: 3319958437

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This book provides a comprehensive overview of modern computer-based techniques for analyzing the structure, properties and dynamics of biomolecules and biomolecular processes. It is organized in four main parts; the first one deals with methodology of molecular simulations; the second one with applications of molecular simulations; the third one introduces bioinformatics methods and the use of experimental information in molecular simulations; the last part reports on selected applications of molecular quantum mechanics. This second edition has been thoroughly revised and updated to include the latest progresses made in the respective field of research.

Multi-conformation Monte Carlo
Multi-conformation Monte Carlo

Author: Vera D. Prytkova

Publisher:

Published: 2017

Total Pages: 52

ISBN-13: 9780355307580

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We present a novel multi-conformation Monte Carlo simulation method that enables the modeling of protein-protein interactions and aggregation in crowded protein solutions. This approach is relevant to a molecular-scale description of realistic biological environments, including the cytoplasm and the extracellular matrix, that are characterized by high concentrations of biomolecular solutes (e.g., 300-400 mg/mL for proteins and nucleic acids in the cytoplasm of Escherichia coli). Simulation of such environments necessitates the inclusion of a large number of protein molecules. Therefore, computationally inexpensive methods, such as rigid-body Brownian dynamics or Monte Carlo simulations, can be particularly useful. However, as we demonstrate herein, the rigid-body representation typically employed in simulations of many-protein systems gives rise to certain artifacts in protein-protein interactions. Our approach allows us to incorporate molecular flexibility in Monte Carlo simulations at low computational cost, thereby eliminating ambiguities arising from structure selection in rigid-body simulations. We benchmark and validate the methodology using simulations of hen egg white lysozyme in solution, a well-studied system for which extensive experimental data, including osmotic second virial coefficients, small-angle scattering structure factors, and multiple structures determined by x-ray and neutron crystallography and solution NMR, as well as rigid-body BD simulation results, are available for comparison.

Computer Simulations of Protein Structures and Interactions
Computer Simulations of Protein Structures and Interactions

Author: Serafin Fraga

Publisher: Springer Science & Business Media

Published: 2013-04-17

Total Pages: 296

ISBN-13: 3642514995

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Protein engineering endeavors to design new peptides and proteins or to change the structural and/or functional characteristics of existing ones for specific purposes, opening the way for the development of new drugs. This work develops in a comprehensive way the theoretical formulation for the methods used in computer-assisted modeling and predictions, starting from the basic concepts and proceeding to the more sophisticated methods, such as Monte Carlo and molecular dynamics. An evaluation of the approximations inherent to the simulations will allow the reader to obtain a perspective of the possible deficiencies and difficulties and approach the task with realistic expectations. Examples from the authors laboratories, as well as from the literature provide useful information.