19 research outputs found
Simulating molecular docking with haptics
Intermolecular binding underlies various metabolic and regulatory processes of the
cell, and the therapeutic and pharmacological properties of drugs. Molecular docking
systems model and simulate these interactions in silico and allow the study of the
binding process. In molecular docking, haptics enables the user to sense the interaction
forces and intervene cognitively in the docking process. Haptics-assisted docking
systems provide an immersive virtual docking environment where the user can interact
with the molecules, feel the interaction forces using their sense of touch, identify
visually the binding site, and guide the molecules to their binding pose. Despite a
forty-year research e�ort however, the docking community has been slow to adopt this
technology. Proprietary, unreleased software, expensive haptic hardware and limits
on processing power are the main reasons for this. Another signi�cant factor is the
size of the molecules simulated, limited to small molecules.
The focus of the research described in this thesis is the development of an interactive
haptics-assisted docking application that addresses the above issues, and enables
the rigid docking of very large biomolecules and the study of the underlying interactions.
Novel methods for computing the interaction forces of binding on the CPU
and GPU, in real-time, have been developed. The force calculation methods proposed
here overcome several computational limitations of previous approaches, such as precomputed
force grids, and could potentially be used to model molecular
exibility
at haptic refresh rates. Methods for force scaling, multipoint collision response, and
haptic navigation are also reported that address newfound issues, particular to the
interactive docking of large systems, e.g. force stability at molecular collision. The
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result is a haptics-assisted docking application, Haptimol RD, that runs on relatively
inexpensive consumer level hardware, (i.e. there is no need for specialized/proprietary
hardware)
Software Introduction: Methodological advances for interacting with biomolecules using haptics
Over the past 15 years we have been developing tools for interacting with biomolecules using haptics. Interactions with biomolecules in the virtual world are made via a haptic-feedback device that is able to resist inputs from the user or even act to move the user’s hand in response to molecular forces. Here we highlight the key methodological advances made in the development of these tools including Haptimol ISAS, a tool for interacting with a molecule’s solvent accessible surface, Haptimol ENM, a tool for applying forces to an elastic network model of a biomolecule, DockIT (formerly Haptimol RD), for interactive rigid docking, and Haptimol FlexiDock, for interactive docking that models flexibility in the receptor molecule
Virtual environment for studying the docking interactions of rigid biomolecules with haptics
Haptic technology facilitates user interaction with the virtual world via the sense of touch. In molecular docking, haptics enables the user to sense the interaction forces during the docking process. Here we describe a haptics-assisted interactive software tool, called Haptimol RD, for the study of docking interactions. By utilising GPU-accelerated proximity querying methods very large systems can now be studied. Methods for force scaling, multipoint collision response and haptic navigation are described that address force stability issues that are particular to the interactive docking of large systems. Thus Haptimol RD expands, for the first time, the use of interactive biomolecular haptics to the study of protein-protein interactions. Unlike existing approaches, Haptimol RD is designed to run on relatively inexpensive consumer-level hardware and is freely available to the community
Adaptive GPU-accelerated force calculation for interactive rigid molecular docking using haptics
Molecular docking systems model and simulate in silico the interactions of intermolecular binding. Haptics-assisted docking enables the user to interact with the simulation via their sense of touch but a stringent time constraint on the computation of forces is imposed due to the sensitivity of the human haptic system. To simulate high fidelity smooth and stable feedback the haptic feedback loop should run at rates of 500 Hz to 1 kHz. We present an adaptive force calculation approach that can be executed in parallel on a wide range of Graphics Processing Units (GPUs) for interactive haptics-assisted docking with wider applicability to molecular simulations. Prior to the interactive session either a regular grid or an octree is selected according to the available GPU memory to determine the set of interatomic interactions within a cutoff distance. The total force is then calculated from this set. The approach can achieve force updates in less than 2 ms for molecular structures comprising hundreds of thousands of atoms each, with performance improvements of up to 90 times the speed of current CPU-based force calculation approaches used in interactive docking. Furthermore, it overcomes several computational limitations of previous approaches such as pre-computed force grids, and could potentially be used to model receptor flexibility at haptic refresh rates
A real-time proximity querying algorithm for haptic-based molecular docking
Intermolecular binding underlies every metabolic and regulatory processes of the cell, and the therapeutic and pharmacological properties of drugs. Molecular docking systems model and simulate these interactions in silico and allow us to study the binding process. Haptic-based docking provides an immersive virtual docking environment where the user can interact with and guide the molecules to their binding pose. Moreover, it allows human perception, intuition and knowledge to assist and accelerate the docking process, and reduces incorrect binding poses. Crucial for interactive docking is the real-time calculation of interaction forces. For smooth and accurate haptic exploration and manipulation, force-feedback cues have to be updated at a rate of 1 kHz. Hence, force calculations must be performed within 1ms. To achieve this, modern haptic-based docking approaches often utilize pre-computed force grids and linear interpolation. However, such grids are time-consuming to pre-compute (especially for large molecules), memory hungry, can induce rough force transitions at cell boundaries and cannot be applied to flexible docking. Here we propose an efficient proximity querying method for computing intermolecular forces in real time. Our motivation is the eventual development of a haptic-based docking solution that can model molecular flexibility. Uniquely in a haptics application we use octrees to decompose the 3D search space in order to identify the set of interacting atoms within a cut-off distance. Force calculations are then performed on this set in real time. The implementation constructs the trees dynamically, and computes the interaction forces of large molecular structures (i.e. consisting of thousands of atoms) within haptic refresh rates. We have implemented this method in an immersive, haptic-based, rigid-body, molecular docking application called Haptimol_RD. The user can use the haptic device to orientate the molecules in space, sense the interaction forces on the device, and guide the molecules to their binding pose. Haptimol_RD is designed to run on consumer level hardware, i.e. there is no need for specialized/proprietary hardware
Interactive flexible-receptor molecular docking in VR using DockIT
Interactive docking enables the user to guide and control the docking of two biomolecules into a binding pose. It is of use when a binding site is known and is thought to be applicable to structure-based drug design (SBDD) and educating students about biomolecular interactions. For SBDD it enables expertise and intuition to be brought to bear in the drug design process. In education, it can teach students about the most basic level of biomolecular function. Here we introduce DockIT for VR that uses a VR headset and hand-held controllers. Using the method of linear response on explicit solvent molecular dynamics simulations, DockIT can model both global and local conformational changes within the receptor due to forces of interaction with the ligand. It has real-time flexible molecular surface rendering and can show the real-time formation and breaking of hydrogen bonds, both between the ligand and receptor, and within the receptor itself as it smoothly changes conformation
Determination of locked interfaces in biomolecular complexes using Haptimol_RD
Interactive haptics-assisted docking provides a virtual environment for the study of molecular complex formation. It enables the user to interact with the virtual molecules, experience the interaction forces via their sense of touch, and gain insights about the docking process itself. Here we use a recently developed haptics software tool, Haptimol_RD, for the rigid docking of protein subunits to form complexes. Dimers, both homo and hetero, are loaded into the software with their subunits separated in space for the purpose of assessing whether they can be brought back into the correct docking pose via rigid-body movements. Four dimers were classified into two types: two with an interwinding subunit interface and two with a non-interwinding subunit interface. It was found that the two with an interwinding interface could not be docked whereas the two with the non-interwinding interface could be. For the two that could be docked a “sucking” effect could be felt on the haptic device when the correct binding pose was approached which is associated with a minimum in the interaction energy. It is clear that for those that could not be docked, the conformation of one or both of the subunits must change upon docking. This leads to the steric-based concept of a locked or non-locked interface. Non-locked interfaces have shapes that allow the subunits to come together or come apart without the necessity of intra-subunit conformational change, whereas locked interfaces require a conformational change within one or both subunits for them to be able to come apart
DockIT: A tool for interactive molecular docking and molecular complex construction
Summary: DockIT is a tool that has a unique set of physical and graphical features for interactive molecular docking. It enables the user to bring a ligand and a receptor into a docking pose by con-trolling the ligand position, either with a mouse and keyboard, or with a haptic device. Atomic inter-actions are modelled using molecular dynamics-based force-fields with the force on the ligand being felt on a haptic device. Real-time calculation and display of intermolecular hydrogen bonds and multipoint collision detection either using maximum force or maximum atomic overlap, mean that together with the ability to monitor selected intermolecular atomic distances, the user can find physically feasible docking poses that satisfy distance constraints derived from experimental methods. With these features and the ability to output and reload docked structures it can be used to accurately build up large multi-component molecular systems in preparation for molecular dy-namics simulation. Availability and Implementation: DockIT is available free of charge for non-commercial use at http://haptimol.co.uk/dockit/dockit.zip. It requires a windows computer with GPU that supports OpenCL 1.2 and OpenGL 4.0. It may be used with a mouse and keyboard, or a haptic device from 3DSystems
Interactive Flexible-Receptor Molecular Docking in Virtual Reality Using DockIT
Interactive docking enables the user to guide and control
the docking
of two biomolecules into a binding pose. It is of particular use when
the binding site is known and is thought to be applicable to structure-based
drug design (SBDD) and educating students about biomolecular interactions.
For SBDD, it enables expertise and intuition to be brought to bear
in the drug design process. In education, it can teach students about
the most basic level of biomolecular function. Here, we introduce
DockIT for virtual reality (VR) that uses a VR headset and hand-held
controllers. Using the method of linear response on explicit solvent
molecular dynamics simulations, DockIT can model both global and local
conformational changes within the receptor due to forces of interaction
with the ligand. It has real-time flexible molecular surface rendering
and can show the real-time formation and breaking of hydrogen bonds,
both between the ligand and receptor and within the receptor itself
as it smoothly changes conformation
Recombinant Human Thyrotropin-Aided Radioiodine Therapy in Tracheal Obstruction by an Invading Well-Differentiated Thyroid Carcinoma
Papillary thyroid carcinomas (PTCs) usually extend to lymph nodes in the neck and mediastinum. Rarely, they invade the neighboring upper airway anatomical structures. We report a 56-year-old woman who presented with symptoms of upper airway obstruction. Imaging studies revealed a lesion derived from the thyroid which invaded and obstructed the trachea, which appeared to be a highly differentiated PTC. Total thyroidectomy was performed, with removal of the endotracheal part of the mass along with the corresponding anterior tracheal rings. Two months later, a whole body I131 scan after recombinant human thyroid-stimulating hormone (rh-TSH) administration was performed and revealed a residual mass in upper left thyroid lobe. Subsequently, 150 mCi I131 were given following rh-TSH administration. Nine months later, there was no sign of residual tumor. This case is the first one reported in the literature regarding rh-TSH administration prior to RAI ablation in a PTC obstructing the trachea