Interactive GPU-based generation of solvent-excluded surfaces

The solvent-excluded surface (SES) is a popular molecular representation that gives the boundary of the molecular volume with respect to a specific solvent. SESs depict which areas of a molecule are accessible by a specific solvent, which is represented as a spherical probe. Despite the popularity of SESs, their generation is still a compute-intensive process, which is often performed in a preprocessing stage prior to the actual rendering (except for small models). For dynamic data or varying probe radii, however, such a preprocessing is not feasible as it prevents interactive visual analysis. Thus, we present a novel approach for the on-the-fly generation of SESs, a highly parallelizable, grid-based algorithm where the SES is rendered using ray-marching. By exploiting modern GPUs, we are able to rapidly generate SESs directly within the mapping stage of the visualization pipeline. Our algorithm can be applied to large time-varying molecules and is scalable, as it can progressively refine the SES if GPU capabilities are insufficient. In this paper, we show how our algorithm is realized and how smooth transitions are achieved during progressive refinement. We further show visual results obtained from real-world data and discuss the performance obtained, which improves upon previous techniques in both the size of the molecules that can be handled and the resulting frame rate.Peer ReviewedPostprint (author's final draft

Advanced Computer Graphics Aided Molecular Visualization and Manipulation Softwares: The Hierarchy of Research Methodologies

In the present day, the huge obstacles, and the major technical problems encountered by the teaching and research faculties, academicians, industrial specialists, laboratory demonstrators and instructors, fellow students and researchers, etc. are to adopt integrative approaches of demonstrating (learning) chemistry and chemical education, and the realistic ways of delivering (grasping) scientific materials articulately with graceful and effortless manner. Towards minimizing these challenges, various audio-visual tools and technologies, advanced computer aided molecular graphics, freely available electronic gadgets assisted chemistry and chemical education apps, human unreadable data reading and accessing softwares, etc. are being incorporated worldwide as the most indispensable physical and electronic means for successful professionalisms. This short article is essentially a collective report underscoring extraordinary approaches, incredible efforts, and innovative skills of the computer based chemical and molecular graphics towards illuminating intrinsic parts of the chemistry and chemical education, and revealing various aspects of the cutting -edge research. As their representatives, herein, the different type computer coding languages based graphical tools such as Molden, GaussView, Jmol, and Visual Molecular Dynamics (VMD) are referred, and elucidated their potential applications and remarkable attempts in the advancement of diverse areas of chemistry and chemical education. Beside this, the most essential graphical features, unique rendering abilities with magnificent views, splendid visualizing skills, awesome data accessing functionalities, etc. of each of them, and their invaluable roles for studying complex molecules, biomolecules, crystals, and the entire material assemblies as well as for investigating global and local molecular physicochemical properties are presented concisely with the special stresses on their relatively better and comparatively more applicable distinctive attributes explicitl

Generating Triangulated Macromolecular Surfaces by Euclidean Distance Transform

Macromolecular surfaces are fundamental representations of their three-dimensional geometric shape. Accurate calculation of protein surfaces is of critical importance in the protein structural and functional studies including ligand-protein docking and virtual screening. In contrast to analytical or parametric representation of macromolecular surfaces, triangulated mesh surfaces have been proved to be easy to describe, visualize and manipulate by computer programs. Here, we develop a new algorithm of EDTSurf for generating three major macromolecular surfaces of van der Waals surface, solvent-accessible surface and molecular surface, using the technique of fast Euclidean Distance Transform (EDT). The triangulated surfaces are constructed directly from volumetric solids by a Vertex-Connected Marching Cube algorithm that forms triangles from grid points. Compared to the analytical result, the relative error of the surface calculations by EDTSurf is <2–4% depending on the grid resolution, which is 1.5–4 times lower than the methods in the literature; and yet, the algorithm is faster and costs less computer memory than the comparative methods. The improvements in both accuracy and speed of the macromolecular surface determination should make EDTSurf a useful tool for the detailed study of protein docking and structure predictions. Both source code and the executable program of EDTSurf are freely available at http://zhang.bioinformatics.ku.edu/EDTSurf

GRAPE: GRaphical Abstracted Protein Explorer

The region surrounding a protein, known as the surface of interaction or molecular surface, can provide valuable insight into its function. Unfortunately, due to the complexity of both their geometry and their surface fields, study of these surfaces can be slow and difficult and important features may be hard to identify. Here, we describe our GRaphical Abstracted Protein Explorer, or GRAPE, a web server that allows users to explore abstracted representations of proteins. These abstracted surfaces effectively reduce the level of detail of the surface of a macromolecule, using a specialized algorithm that removes small bumps and pockets, while preserving large-scale structural features. Scalar fields, such as electrostatic potential and hydropathy, are smoothed to further reduce visual complexity. This entirely new way of looking at proteins complements more traditional views of the molecular surface. GRAPE includes a thin 3D viewer that allows users to quickly flip back and forth between both views. Abstracted views provide a fast way to assess both a molecule's shape and its different surface field distributions. GRAPE is freely available at http://grape.uwbacter.org

Exploration of Reaction Pathways and Chemical Transformation Networks

For the investigation of chemical reaction networks, the identification of all relevant intermediates and elementary reactions is mandatory. Many algorithmic approaches exist that perform explorations efficiently and automatedly. These approaches differ in their application range, the level of completeness of the exploration, as well as the amount of heuristics and human intervention required. Here, we describe and compare the different approaches based on these criteria. Future directions leveraging the strengths of chemical heuristics, human interaction, and physical rigor are discussed.Comment: 48 pages, 4 figure

Between Algorithm and Model: Different Molecular Surface Definitions for the Poisson-Boltzmann based Electrostatic Characterization of Biomolecules in Solution

The definition of a molecular surface which is physically sound and computationally efficient is a very interesting and long standing problem in the implicit solvent continuum modeling of biomolecular systems as well as in the molecular graphics field. In this work, two molecular surfaces are evaluated with respect to their suitability for electrostatic computation as alternatives to the widely used Connolly-Richards surface: the blobby surface, an implicit Gaussian atom centered surface, and the skin surface. As figures of merit, we considered surface differentiability and surface area continuity with respect to atom positions, and the agreement with explicit solvent simulations. Geometric analysis seems to privilege the skin to the blobby surface, and points to an unexpected relationship between the non connectedness of the surface, caused by interstices in the solute volume, and the surface area dependence on atomic centers. In order to assess the ability to reproduce explicit solvent results, specific software tools have been developed to enable the use of the skin surface in Poisson-Boltzmann calculations with the DelPhi solver. Results indicate that the skin and Connolly surfaces have a comparable performance from this last point of view