Exploration of disorder in protein structures by X-ray restrained molecular dynamics

1991 ◽  
Vol 10 (4) ◽  
pp. 340-358 ◽  
Author(s):  
John Kuriyan ◽  
Klara Ösapay ◽  
Stephen K. Burley ◽  
Axel T. Brünger ◽  
Wayne A. Hendrickson ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Protein Structures ◽  
X Ray ◽  
Restrained Molecular Dynamics

Structural refinement by restrained molecular-dynamics algorithm with small-angle X-ray scattering constraints for a biomolecule

2004 ◽  
Vol 37 (1) ◽  
pp. 103-109 ◽  
Author(s):  
Masaki Kojima ◽  
Alexander A. Timchenko ◽  
Junichi Higo ◽  
Kazuki Ito ◽  
Hiroshi Kihara ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
Small Angle ◽  
Protein Structures ◽  
Saxs Data ◽  
X Ray ◽  
X Ray Scattering ◽  
Saxs Curve ◽  
Restrained Molecular Dynamics ◽  
Ray Scattering

A new algorithm to refine protein structures in solution from small-angle X-ray scattering (SAXS) data was developed based on restrained molecular dynamics (MD). In the method, the sum of squared differences between calculated and observed SAXS intensities was used as a constraint energy function, and the calculation was started from given atomic coordinates, such as those of the crystal. In order to reduce the contribution of the hydration effect to the deviation from the experimental (objective) curve during the dynamics, and purely as an estimate of the efficiency of the algorithm, the calculation was first performed assuming the SAXS curve corresponding to the crystal structure as the objective curve. Next, the calculation was carried out with `real' experimental data, which yielded a structure that satisfied the experimental SAXS curve well. The SAXS data for ribonuclease T1, a single-chain globular protein, were used for the calculation, along with its crystal structure. The results showed that the present algorithm was very effective in the refinement and adjustment of the initial structure so that it could satisfy the objective SAXS data.

scholarly journals xMDFF: molecular dynamics flexible fitting of low-resolution X-ray structures

2014 ◽  
Vol 70 (9) ◽  
pp. 2344-2355 ◽  
Author(s):  
Ryan McGreevy ◽  
Abhishek Singharoy ◽  
Qufei Li ◽  
Jingfen Zhang ◽  
Dong Xu ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Large Scale ◽  
Protein Structures ◽  
Data Bank ◽  
Real Space ◽  
Low Resolution ◽  
X Ray ◽  
X Ray Crystallography ◽  
Atomic Structures ◽  
Electron Density Map

X-ray crystallography remains the most dominant method for solving atomic structures. However, for relatively large systems, the availability of only medium-to-low-resolution diffraction data often limits the determination of all-atom details. A new molecular dynamics flexible fitting (MDFF)-based approach, xMDFF, for determining structures from such low-resolution crystallographic data is reported. xMDFF employs a real-space refinement scheme that flexibly fits atomic models into an iteratively updating electron-density map. It addresses significant large-scale deformations of the initial model to fit the low-resolution density, as tested with synthetic low-resolution maps of D-ribose-binding protein. xMDFF has been successfully applied to re-refine six low-resolution protein structures of varying sizes that had already been submitted to the Protein Data Bank. Finally,viasystematic refinement of a series of data from 3.6 to 7 Å resolution, xMDFF refinements together with electrophysiology experiments were used to validate the first all-atom structure of the voltage-sensing protein Ci-VSP.

scholarly journals Anomalies in the refinement of isoleucine

2014 ◽  
Vol 70 (4) ◽  
pp. 1037-1049 ◽  
Author(s):  
Karen R. M. Berntsen ◽  
Gert Vriend
Keyword(s):  
Molecular Dynamics ◽  
High Resolution ◽  
Secondary Structure ◽  
Protein Structures ◽  
Side Chain ◽  
Energy Functions ◽  
Torsion Angles ◽  
X Ray ◽  
X Ray Crystallography ◽  
Target Values

A study of isoleucines in protein structures solved using X-ray crystallography revealed a series of systematic trends for the two side-chain torsion angles χ1and χ2dependent on the resolution, secondary structure and refinement software used. The average torsion angles for the nine rotamers were similar in high-resolution structures solved using either theREFMAC,CNSorPHENIXsoftware. However, at low resolution these programs often refine towards somewhat different χ1and χ2values. Small systematic differences can be observed between refinement software that uses molecular dynamics-type energy terms (for exampleCNS) and software that does not use these terms (for exampleREFMAC). Detailing the standard torsion angles used in refinement software can improve the refinement of protein structures. The target values in the molecular dynamics-type energy functions can also be improved.

Real-Space X-Ray Pair Distribution Function Analysis and Molecular-Dynamics Modelling of Diflunisal Channel Hydrates

2020 ◽  
Author(s):  
Anuradha Pallipurath ◽  
Francesco Civati ◽  
Jonathan Skelton ◽  
Dean Keeble ◽  
Clare Crowley ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Distribution Function ◽  
Structural Dynamics ◽  
First Principles ◽  
Pair Distribution Function ◽  
Function Analysis ◽  
Real Space ◽  
X Ray ◽  
Dynamics Modelling ◽  
Dynamics Simulations

X-ray pair distribution function analysis is used with first-principles molecular dynamics simulations to study the co-operative H<sub>2</sub>O binding, structural dynamics and host-guest interactions in the channel hydrate of diflunisal.

Improved Sampling Strategies for Protein Model Refinement based on Molecular Dynamics Simulation

2020 ◽  
Author(s):  
Lim Heo ◽  
Collin Arbour ◽  
Michael Feig
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Structure Prediction ◽  
Protein Structures ◽  
Conformational Space ◽  
Dynamics Simulation ◽  
Model Refinement ◽  
Protein Model ◽  
Lower Accuracy ◽  
Simulation Based

Protein structures provide valuable information for understanding biological processes. Protein structures can be determined by experimental methods such as X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, or cryogenic electron microscopy. As an alternative, in silico methods can be used to predict protein structures. Those methods utilize protein structure databases for structure prediction via template-based modeling or for training machine-learning models to generate predictions. Structure prediction for proteins distant from proteins with known structures often results in lower accuracy with respect to the true physiological structures. Physics-based protein model refinement methods can be applied to improve model accuracy in the predicted models. Refinement methods rely on conformational sampling around the predicted structures, and if structures closer to the native states are sampled, improvements in the model quality become possible. Molecular dynamics simulations have been especially successful for improving model qualities but although consistent refinement can be achieved, the improvements in model qualities are still moderate. To extend the refinement performance of a simulation-based protocol, we explored new schemes that focus on an optimized use of biasing functions and the application of increased simulation temperatures. In addition, we tested the use of alternative initial models so that the simulations can explore conformational space more broadly. Based on the insight of this analysis we are proposing a new refinement protocol that significantly outperformed previous state-of-the-art molecular dynamics simulation-based protocols in the benchmark tests described here. <br>

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