scholarly journals Evidence vs Expectations: How to validate your ligand in a protein structure

2014 ◽  
Vol 70 (a1) ◽  
pp. C1479-C1479
Author(s):  
Edwin Pozharski
Keyword(s):  
Structural Biology ◽  
Complex Structure ◽  
Structural Data ◽  
High Expectation ◽  
Ligand Complex ◽  
Ligand Interaction ◽  
Protein Ligand Interaction ◽  
Experimental Findings ◽  
Small Molecule Ligand

Determination of a protein-ligand complex structure is essential in many areas of structural biology. Details of the interactions between protein and a small molecule ligand often represent major findings from a crystal structure. Thorough validation of interpretation of such structural data is particularly important given high expectation of confirming prior experimental findings regarding targeted protein-ligand interaction. Modern methods of ligand validation are discussed and illustrated.

scholarly journals Protein–ligand complex structure from serial femtosecond crystallography using soaked thermolysin microcrystals and comparison with structures from synchrotron radiation

2017 ◽  
Vol 73 (8) ◽  
pp. 702-709 ◽  
Author(s):  
Hisashi Naitow ◽  
Yoshinori Matsuura ◽  
Kensuke Tono ◽  
Yasumasa Joti ◽  
Takashi Kameshima ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Room Temperature ◽  
Complex Structure ◽  
Binding Mode ◽  
Ligand Complex ◽  
X Ray ◽  
Cell Parameters ◽  
Serial Femtosecond Crystallography ◽  
Small Molecule Ligand

Serial femtosecond crystallography (SFX) with an X-ray free-electron laser is used for the structural determination of proteins from a large number of microcrystals at room temperature. To examine the feasibility of pharmaceutical applications of SFX, a ligand-soaking experiment using thermolysin microcrystals has been performed using SFX. The results were compared with those from a conventional experiment with synchrotron radiation (SR) at 100 K. A protein–ligand complex structure was successfully obtained from an SFX experiment using microcrystals soaked with a small-molecule ligand; both oil-based and water-based crystal carriers gave essentially the same results. In a comparison of the SFX and SR structures, clear differences were observed in the unit-cell parameters, in the alternate conformation of side chains, in the degree of water coordination and in the ligand-binding mode.

scholarly journals WONKAandOOMMPPAA: analysis of protein–ligand interaction data to direct structure-based drug design

2017 ◽  
Vol 73 (3) ◽  
pp. 279-285
Author(s):  
Charlotte M. Deane ◽  
Ian D. Wall ◽  
Darren V. S. Green ◽  
Brian D. Marsden ◽  
Anthony R. Bradley
Keyword(s):  
Three Dimensional ◽  
Structural Data ◽  
Data Sets ◽  
Interaction Data ◽  
Activity Data ◽  
Ligand Interaction ◽  
Structure Based Drug Design ◽  
Web Based ◽  
Protein Ligand Interaction ◽  
Ligand Activity

In this work, two freely available web-based interactive computational tools that facilitate the analysis and interpretation of protein–ligand interaction data are described. Firstly,WONKA, which assists in uncovering interesting and unusual features (for example residue motions) within ensembles of protein–ligand structures and enables the facile sharing of observations between scientists. Secondly,OOMMPPAA, which incorporates protein–ligand activity data with protein–ligand structural data using three-dimensional matched molecular pairs.OOMMPPAAhighlights nuanced structure–activity relationships (SAR) and summarizes available protein–ligand activity data in the protein context. In this paper, the background that led to the development of both tools is described. Their implementation is outlined and their utility using in-house Structural Genomics Consortium (SGC) data sets and openly available data from the PDB and ChEMBL is described. Both tools are freely available to use and download at http://wonka.sgc.ox.ac.uk/WONKA/ and http://oommppaa.sgc.ox.ac.uk/OOMMPPAA/.

scholarly journals Identification of the first small-molecule ligand of the neuronal receptor sortilin and structure determination of the receptor–ligand complex

2014 ◽  
Vol 70 (2) ◽  
pp. 451-460 ◽  
Author(s):  
Jacob Lauwring Andersen ◽  
Tenna Juul Schrøder ◽  
Søren Christensen ◽  
Dorthe Strandbygård ◽  
Lone Tjener Pallesen ◽  
...  
Keyword(s):  
Small Molecule ◽  
Binding Mode ◽  
Membrane Glycoprotein ◽  
Type I ◽  
Ligand Complex ◽  
Neuronal Viability ◽  
The Central Nervous System ◽  
Vacuolar Protein ◽  
Small Molecule Ligand

Sortilin is a type I membrane glycoprotein belonging to the vacuolar protein sorting 10 protein (Vps10p) family of sorting receptors and is most abundantly expressed in the central nervous system. Sortilin has emerged as a key player in the regulation of neuronal viability and has been implicated as a possible therapeutic target in a range of disorders. Here, the identification of AF40431, the first reported small-molecule ligand of sortilin, is reported. Crystals of the sortilin–AF40431 complex were obtained by co-crystallization and the structure of the complex was solved to 2.7 Å resolution. AF40431 is bound in the neurotensin-binding site of sortilin, with the leucine moiety of AF40431 mimicking the binding mode of the C-terminal leucine of neurotensin and the 4-methylumbelliferone moiety of AF40431 forming π-stacking with a phenylalanine.

scholarly journals Analysis of the Quality of Macromolecular Structures

2017 ◽  
Author(s):  
Dinakar M. Salunke
Keyword(s):  
Structural Biology ◽  
Model Building ◽  
Structural Data ◽  
Data Bank ◽  
X Ray Crystallography ◽  
Structure Factors ◽  
Scientific Systems ◽  
Published Research

AbstractStructure determination utilizing X-ray crystallography involves collection of diffraction data, determination of initial phases followed by iterative rounds of model building and crystallographic refinement to improve the phases and minimize the differences between calculated and observed structure factors. At each of these stages, a variety of statistical filters exist to ensure appropriate validation. Biologically important observations often come from interpretations of signals that need to be carefully deciphered from noise and therefore human intervention is as important as the automated filters. Currently, all structural data are deposited in the Protein Data Bank and this repository is continuously evolving to incorporate possible new improvements in macromolecular crystallography. The journals that publish data arising from structural studies modulate their policies to take cognizance of new improved methodologies. The PDB and journals have evolved an accepted protocol to ensure the integrity of crystallographic results. As a result, the quality of available data and interpretations are becoming better over the years. However, there have been periodic efforts by some individuals who misuse validation mechanisms to selectively target published research through spurious challenges. These actions do more harm to the field of structural biology and runs counter to their claim to cleanse the system. The scientific systems in structural biology are robust and capable of self-correction and unwarranted vigilantism is counterproductive.

Stirring rate affects thermodynamics and unfolding kinetics in isothermal titration calorimetry

2020 ◽  
Vol 168 (1) ◽  
pp. 53-62
Author(s):  
Takahiro Maruno ◽  
Tadayasu Ohkubo ◽  
Susumu Uchiyama
Keyword(s):  
Thermodynamic Parameters ◽  
Isothermal Titration Calorimetry ◽  
Titration Calorimetry ◽  
Reaction Heat ◽  
Ligand Interaction ◽  
New Approach ◽  
Stirring Rate ◽  
Protein Ligand Interaction ◽  
Unfolding Kinetics

Abstract Isothermal titration calorimetry (ITC) directly provides thermodynamic parameters depicting the energetics of intermolecular interactions in solution. During ITC experiments, a titration syringe with a paddle is continuously rotating to promote a homogeneous mixing. Here, we clarified that the shape of the paddles (flat, corkscrew and small-pitched corkscrew) and the stirring rates influence on the thermodynamic parameters of protein–ligand interaction. Stirring with the flat paddle at lower and higher rate both yielded a lower exothermic heat due to different reasons. The complete reaction with no incompetent fractions was achieved only when the stirring was performed at 500 or 750 rpm using the small-pitched corkscrew paddle. The evaluation of the protein solution after 1,500 rpm stirring indicated that proteins in the soluble fraction decreased to 94% of the initial amount, among which 6% was at an unfolded state. In addition, a significant increase of micron aggregates was confirmed. Furthermore, a new approach for the determination of the unfolding kinetics based on the time dependence of the total reaction heat was developed. This study demonstrates that a proper stirring rate and paddle shape are essential for the reliable estimation of thermodynamic parameters in ITC experiments.

Homology Modeling of Mus Musculus CDK5 and Molecular Docking Studies with Flavonoids

2017 ◽  
Vol 9 (6) ◽  
Author(s):  
Sowmya Suri ◽  
Rumana Waseem ◽  
Seshagiri Bandi ◽  
Sania Shaik
Keyword(s):  
Molecular Docking ◽  
3D Model ◽  
Structural Features ◽  
Docking Studies ◽  
Amino Acid Residues ◽  
Cyclin Dependent Kinase ◽  
Ligand Complex ◽  
Ligand Interaction ◽  
Molecular Docking Studies ◽  
Cyclin Dependent Kinase 5

A 3D model of Cyclin-dependent kinase 5 (CDK5) (Accession Number: Q543f6) is generated based on crystal structure of P. falciparum PFPK5-indirubin-5-sulphonate ligand complex (PDB ID: 1V0O) at 2.30 Å resolution was used as template. Protein-ligand interaction studies were performed with flavonoids to explore structural features and binding mechanism of flavonoids as CDK5 (Cyclin-dependent kinase 5) inhibitors. The modelled structure was selected on the basis of least modeler objective function. The model was validated by PROCHECK. The predicted 3D model is reliable with 93.0% of amino acid residues in core region of the Ramachandran plot. Molecular docking studies with flavonoids viz., Diosmetin, Eriodictyol, Fortuneletin, Apigenin, Ayanin, Baicalein, Chrysoeriol and Chrysosplenol-D with modelled protein indicate that Diosmetin is the best inhibitor containing docking score of -8.23 kcal/mol. Cys83, Lys89, Asp84. The compound Diosmetin shows interactions with Cys83, Lys89, and Asp84.

scholarly journals Two Rules on the Protein-Ligand Interaction

2008 ◽  
Author(s):  
Xiaodong Pang ◽  
Linxiang Zhou ◽  
Lily Zhang ◽  
Lina Xu ◽  
Xinyi Zhang
Keyword(s):  
Ligand Interaction ◽  
Protein Ligand Interaction

scholarly journals Protein-ligand free energies of binding from full-protein DFT calculations: convergence and choice of exchange-correlation functional

2021 ◽  
Author(s):  
Lennart Gundelach ◽  
Christofer S Tautermann ◽  
Thomas Fox ◽  
Chris-Kriton Skylaris
Keyword(s):  
Drug Discovery ◽  
Ligand Binding ◽  
Dft Calculations ◽  
Quantum Mechanical ◽  
Free Energies ◽  
Ligand Interaction ◽  
Exchange Correlation ◽  
Ligand Free ◽  
Protein Ligand Interaction ◽  
Binding Free Energies

The accurate prediction of protein-ligand binding free energies with tractable computational methods has the potential to revolutionize drug discovery. Modeling the protein-ligand interaction at a quantum mechanical level, instead of...

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