Conformational free energy maps for globobiose (a-D-Galp-(1-4)-b-D-Galp) in implicit and explict aqueous solution

Four Ramachandran maps of the conformational potential of mean force (PMF) for the galactose disaccharide globobiose(alpha-D-Galp-(1-4)-beta-D-Galp) were calculated in vacuum, explicit water, with a simple high dielectric constant and a distance dependent dielectric coefficient, respectively. This simple model of the galactanalpha-(1-4)-linkage is shown to be conformationallyrestricted, with only a small range of syn-phi syn-psi conformations predominating at standard temperature and pressure. This has implications for the preferred conformation and chain dynamics of alpha-galactosides. In addition, comparison of the relevant PMF surfaces reveals the substitution of a high dielectric constant for explicit water solution to be a valid approximation for reproducing the minimum energy conformation of this glycosidic linkage

Techniques for visualization of carbohydrate molecules

Standard molecular visualizations, such as the classic ball-and-stick model, are not suitable for large, complex molecules because the overall molecular structure is obscured by the atomic detail. For proteins, the more abstract ribbon and cartoon representations are instead used to reveal large scale molecular conformation and connectivity. However, there is currently no accepted convention for simplifying oligo- and polysaccharide structures. We introduce two novel visualization algorithms for carbohydrates, incorporated into a visualization package, CarboHydra. Both algorithms highlight the sugar rings and backbone conformation of the carbohydrate chain, ignoring ring substituents. The first algorithm, termed PaperChain, emphasizes the type and conformation of the carbohydrate rings. The second, Twister, emphasizes the relative orientation of the rings. We further include two rendering enhancements to augment these visualizations: silhouettes edges and a translucent overlay of the ball-and-stick atomic representation. To demonstrate their utility, the algorithms and visualization enhancements are here applied to a variety of carbohydrate molecules. User evaluations indicate that they present a more useful view of carbohydrate structure than the standard ball-and-stick representation. The algorithms were found to be complementary, with PaperChain particularly effective for smaller carbohydrates and Twister useful at larger scales for highlighting the backbone twist of polysaccharides

Improving the usability of scientific software with participatory design: a new interface design for radio astronomy visualisation software

The importance of usability considerations in software development is well recognised. However, typically usability is not considered as an explicit goal in the development of scientific software, which is often done by developers with domain-specific knowledge but little formal software development training. In interactive software developed for international collaborations such as the Square Kilometre Array, usability is increasingly important. A possible solution is persistent collaboration between software developers and domain experts to design effective user interfaces. Here we carry out a User Centred participatory design approach to designing an astronomy visualisation interface. The methodology is iterative: in each iteration, a prototype interface was designed and then evaluated by users. Frequent consultation with domain experts produced an innovative design for an astronomy visualisation interface with improved usability

Visualization of Solution Sets from Automated Docking of Molecular Structures

Aligning structures, often referred to as docking or registration, is frequently required in fields such as computer science, robotics and structural biology. The task of aligning the structures is usually automated, but due to noise and imprecision, the user often needs to evaluate the results before a final decision can be made. The solutions involved are of a multidimensional nature and normally densely populated. Therefore, some form of visualization is necessary, especially if users want to achieve higher level understanding, such as solution symmetry or clustering, from the data. We have developed a system that provides two views of the data. One view places focus on the orientation of the solutions and the other focuses on translations. Solutions within the views are crosslinked using various visual cues. Users are also able to apply various filters, intelligently reducing the solution set. We applied the visualization to data generated by the automated cryo-EM process of docking molecular structures into electron density maps. Current systems in this field only allow for visual representation of a single solution or a numerical list of the data. We evaluated the system through a multi-phase user study and found that the users were able to gain a better high-level understanding of the data, even in cases of relatively small solution sets