| 1. |
- Strömbergsson, Helena, 1975-, et al.
(författare)
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Interaction Model Based on Local Protein Substructures Generalizes to the Entire Structural Enzyme-Ligand Space
- 2008
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Ingår i: Journal of chemical information and modelling. - : American Chemical Society (ACS). - 1549-960X .- 1549-9596. ; 48:11, s. 2278-2288
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Tidskriftsartikel (refereegranskat)abstract
- Chemogenomics is a new strategy in in silico drug discovery, where the ultimate goal is to understand molecular recognition for all molecules interacting with all proteins in the proteome. To study such cross interactions, methods that can generalize over proteins that vary greatly in sequence, structure, and function are needed. We present a general quantitative approach to protein−ligand binding affinity prediction that spans the entire structural enzyme-ligand space. The model was trained on a data set composed of all available enzymes cocrystallized with druglike ligands, taken from four publicly available interaction databases, for which a crystal structure is available. Each enzyme was characterized by a set of local descriptors of protein structure that describe the binding site of the cocrystallized ligand. The ligands in the training set were described by traditional QSAR descriptors. To evaluate the model, a comprehensive test set consisting of enzyme structures and ligands was manually curated. The test set contained enzyme-ligand complexes for which no crystal structures were available, and thus the binding modes were unknown. The test set enzymes were therefore characterized by matching their entire structures to the local descriptor library constructed from the training set. Both the training and the test set contained enzyme-ligand complexes from all major enzyme classes, and the enzymes spanned a large range of sequences and folds. The experimental binding affinities (pKi) ranged from 0.5 to 11.9 (0.7−11.0 in the test set). The induced model predicted the binding affinities of the external test set enzyme-ligand complexes with an r2 of 0.53 and an RMSEP of 1.5. This demonstrates that the use of local descriptors makes it possible to create rough predictive models that can generalize over a wide range of protein targets.
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| 2. |
- Alvarsson, Jonathan, 1981-
(författare)
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Ligand-based Methods for Data Management and Modelling
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Drug discovery is a complicated and expensive process in the billion dollar range. One way of making the drug development process more efficient is better information handling, modelling and visualisation. The majority of todays drugs are small molecules, which interact with drug targets to cause an effect. Since the 1980s large amounts of compounds have been systematically tested by robots in so called high-throughput screening. Ligand-based drug discovery is based on modelling drug molecules. In the field known as Quantitative Structure–Activity Relationship (QSAR) molecules are described by molecular descriptors which are used for building mathematical models. Based on these models molecular properties can be predicted and using the molecular descriptors molecules can be compared for, e.g., similarity. Bioclipse is a workbench for the life sciences which provides ligand-based tools through a point and click interface. The aims of this thesis were to research, and develop new or improved ligand-based methods and open source software, and to work towards making these tools available for users through the Bioclipse workbench. To this end, a series of molecular signature studies was done and various Bioclipse plugins were developed.An introduction to the field is provided in the thesis summary which is followed by five research papers. Paper I describes the Bioclipse 2 software and the Bioclipse scripting language. In Paper II the laboratory information system Brunn for supporting work with dose-response studies on microtiter plates is described. In Paper III the creation of a molecular fingerprint based on the molecular signature descriptor is presented and the new fingerprints are evaluated for target prediction and found to perform on par with industrial standard commercial molecular fingerprints. In Paper IV the effect of different parameter choices when using the signature fingerprint together with support vector machines (SVM) using the radial basis function (RBF) kernel is explored and reasonable default values are found. In Paper V the performance of SVM based QSAR using large datasets with the molecular signature descriptor is studied, and a QSAR model based on 1.2 million substances is created and made available from the Bioclipse workbench.
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| 3. |
- Eklund, Martin, 1978-
(författare)
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eScience Approaches to Model Selection and Assessment : Applications in Bioinformatics
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- High-throughput experimental methods, such as DNA and protein microarrays, have become ubiquitous and indispensable tools in biology and biomedicine, and the number of high-throughput technologies is constantly increasing. They provide the power to measure thousands of properties of a biological system in a single experiment and have the potential to revolutionize our understanding of biology and medicine. However, the high expectations on high-throughput methods are challenged by the problem to statistically model the wealth of data in order to translate it into concrete biological knowledge, new drugs, and clinical practices. In particular, the huge number of properties measured in high-throughput experiments makes statistical model selection and assessment exigent. To use high-throughput data in critical applications, it must be warranted that the models we construct reflect the underlying biology and are not just hypotheses suggested by the data. We must furthermore have a clear picture of the risk of making incorrect decisions based on the models. The rapid improvements of computers and information technology have opened up new ways of how the problem of model selection and assessment can be approached. Specifically, eScience, i.e. computationally intensive science that is carried out in distributed network envi- ronments, provides computational power and means to efficiently access previously acquired scientific knowledge. This thesis investigates how we can use eScience to improve our chances of constructing biologically relevant models from high-throughput data. Novel methods for model selection and assessment that leverage on computational power and on prior scientific information to "guide" the model selection to models that a priori are likely to be relevant are proposed. In addition, a software system for deploying new methods and make them easily accessible to end users is presented.
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| 4. |
- Lapins, Maris, et al.
(författare)
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A Unified Proteochemometric Model for Prediction of Inhibition of Cytochrome P450 Isoforms
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:6, s. e66566-
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Tidskriftsartikel (refereegranskat)abstract
- A unified proteochemometric (PCM) model for the prediction of the ability of drug-like chemicals to inhibit five major drug metabolizing CYP isoforms (i.e. CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4) was created and made publicly available under the Bioclipse Decision Support open source system at www.cyp450model.org. In regards to the proteochemometric modeling we represented the chemical compounds by molecular signature descriptors and the CYP-isoforms by alignment-independent description of composition and transition of amino acid properties of their protein primary sequences. The entire training dataset contained 63 391 interactions and the best PCM model was obtained using signature descriptors of height 1, 2 and 3 and inducing the model with a support vector machine. The model showed excellent predictive ability with internal AUC = 0.923 and an external AUC = 0.940, as evaluated on a large external dataset. The advantage of PCM models is their extensibility making it possible to extend our model for new CYP isoforms and polymorphic CYP forms. A key benefit of PCM is that all proteins are confined in one single model, which makes it generally more stable and predictive as compared with single target models. The inclusion of the model in Bioclipse Decision Support makes it possible to make virtual instantaneous predictions (∼100 ms per prediction) while interactively drawing or modifying chemical structures in the Bioclipse chemical structure editor.
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| 5. |
- Shoombuatong, Watshara, et al.
(författare)
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Towards Predicting the Cytochrome P450 Modulation : From QSAR to proteochemometric modeling.
- 2017
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Ingår i: Current drug metabolism. - : Bentham Science Publishers Ltd.. - 1389-2002 .- 1875-5453. ; 18:6, s. 540-555
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Tidskriftsartikel (refereegranskat)abstract
- Drug metabolism determines the fate of a drug when it enters the human body and is a critical factor in defining their absorption, distribution, metabolism, excretion and toxicity (ADMET) characteristics. Among the various drug metabolizing enzymes, cytochrome P450s (CYP450) constitute an important protein family that aside from functioning in xenobiotic metabolism is also responsible for a diverse array of other roles encompassing steroid and cholesterol biosynthesis, fatty acid metabolism, calcium homeostasis, neuroendocrine functions and growth regulation. Although CYP450 typically convert xenobiotics into safe metabolites, there are some situations whereby the metabolite is more toxic than its parent molecule. Computational modeling has been instrumental in CYP450 research by rationalizing the nature of the binding event (i.e. inhibit or induce CYP450s) or metabolic stability of query compounds of interest. A plethora of computational approaches encompassing ligand, structure and systems based approaches have been utilized to model CYP450-ligand interactions. This review provides a brief background on the CYP450 family (i.e. its roles, advantages and disadvantages as well as its modulators) and then discusses the various computational approaches that have been used to model CYP450-ligand interaction. Particular focus is given to the use of quantitative structure-activity relationship (QSAR) and more recent proteochemometric modeling studies. Finally, a perspective on the current state of the art and future trends of the field is provided.
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| 6. |
- Simeon, Saw, et al.
(författare)
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Origin of aromatase inhibitory activity via proteochemometric modeling
- 2016
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Ingår i: PeerJ. - : PeerJ. - 2167-8359. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Aromatase, the rate-limiting enzyme that catalyzes the conversion of androgen to estrogen, plays an essential role in the development of estrogen-dependent breast cancer. Side effects due to aromatase inhibitors (AIs) necessitate the pursuit of novel inhibitor candidates with high selectivity, lower toxicity and increased potency. Designing a novel therapeutic agent against aromatase could be achieved computationally by means of ligand-based and structure-based methods. For over a decade, we have utilized both approaches to design potential AIs for which quantitative structure-activity relationships and molecular docking were used to explore inhibitory mechanisms of AIs towards aromatase. However, such approaches do not consider the effects that aromatase variants have on different AIs. In this study, proteochemometrics modeling was applied to analyze the interaction space between AIs and aromatase variants as a function of their substructural and amino acid features. Good predictive performance was achieved, as rigorously verified by 10-fold cross-validation, external validation, leave-one-compound-out cross-validation, leave-one-protein-out cross-validation and Y-scrambling tests. The investigations presented herein provide important insights into the mechanisms of aromatase inhibitory activity that could aid in the design of novel potent AIs as breast cancer therapeutic agents.
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| 7. |
- Spjuth, Ola, 1977-
(författare)
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Bioclipse : Integration of Data and Software in the Life Sciences
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- New high throughput experimental techniques have turned the life sciences into a data-intensive field. Scientists are faced with new types of problems, such as managing voluminous sources of information, integrating heterogeneous data, and applying the proper analysis algorithms; all to end up with reliable conclusions. These challenges call for an infrastructure of algorithms and technologies to supply researchers with the tools and methods necessary to maximize the usefulness of the data. eScience has emerged as a promising technology to take on these challenges, and denotes integrated science carried out in highly distributed network environments, or science that makes use of large data sets and requires high performance computing resources. In this thesis I present standards, exchange formats, algorithms, and software implementations for empowering researchers in the life sciences with the tools of eScience. The work is centered around Bioclipse - an extensible workbench developed in the frame of this thesis - which provides users with instruments for carrying out integrated research and where technical details are hidden under simple graphical interfaces. Bioclipse is a Rich Client that takes full advantage of the many offerings of eScience, such as networked databases and online services. The benefits of mixing local and remote software in a unifying platform are demonstrated with an integrated approach for predicting metabolic sites in chemical structures. To overcome the limitations of the commonly used technologies for interacting with networked services, I also present a new technology using the XMPP protocol. This enables service discovery and asynchronous communication between the client and server, which is ideal for long-running analyses. To maximize the usefulness of the available data there is a need for standards, ontologies, and exchange formats, in order to define what information should be captured and how it should be structured and exchanged. A novel format for exchanging QSAR data sets in a fully interoperable and reproducible form is presented, together with an implementation in Bioclipse that takes advantage of eScience components during the setup process. Bioclipse has been well received by the scientific community, attracted a large group of international users and developers, and has been awarded three international prizes for its innovative character. With continued development, the project has a good chance of becoming an important component in a sustainable infrastructure for the life sciences.
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| 8. |
- Spjuth, Ola, 1977-, et al.
(författare)
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Bioclipse 2: A scriptable integration platform for the life sciences
- 2009
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Ingår i: BMC Bioinformatics. - : Springer Science and Business Media LLC. - 1471-2105. ; 10, s. 397-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Contemporary biological research integrates neighboring scientific domains to answer complex ques- tions in fields such as systems biology and drug discovery. This calls for tools that are intuitive to use, yet flexible to adapt to new tasks. Results: Bioclipse is a free, open source workbench with advanced features for the life sciences. Version 2.0 constitutes a complete rewrite of Bioclipse, and delivers a stable, scalable integration platform for developers and an intuitive workbench for end users. All functionality is available both from the graphical user interface and from a built-in novel domain-specific language, supporting the scientist in interdisciplinary research and reproducible analyses through advanced visualization of the inputs and the results. New components for Bioclipse 2 include a rewritten editor for chemical structures, a table for multiple molecules that supports gigabyte-sized files, as well as a graphical editor for sequences and alignments. Conclusions: Bioclipse 2 is equipped with advanced tools required to carry out complex analysis in the fields of bio- and cheminformatics. Developed as a Rich Client based on Eclipse, Bioclipse 2 leverages on today’s powerful desktop computers for providing a responsive user interface, but also takes full advantage of the Web and networked (Web/Cloud) services for more demanding calculations or retrieval of data. That Bioclipse 2 is based on an advanced and widely used service platform ensures wide extensibility, and new algorithms, visualizations as well as scripting commands can easily be added. The intuitive tools for end users and the extensible architecture make Bioclipse 2 ideal for interdisciplinary and integrative research. Bioclipse 2 is released under the Eclipse Public License (EPL), a flexible open source license that allows additional plugins to be of any license. Bioclipse 2 is implemented in Java and supported on all major platforms; Source code and binaries are freely available at http://www.bioclipse.net.
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| 9. |
- Spjuth, Ola, 1977-, et al.
(författare)
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Bioclipse-R : Integrating management and visualization of life science data with statistical analysis
- 2013
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Ingår i: Bioinformatics. - : Oxford University Press. - 1367-4803 .- 1367-4811. ; 29:2, s. 286-289
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Tidskriftsartikel (refereegranskat)abstract
- Bioclipse, a graphical workbench for the life sciences, provides functionality for managing and visualizing life science data. We introduce Bioclipse-R, which integrates Bioclipse and the statistical programming language R. The synergy between Bioclipse and R is demonstrated by the construction of a decision support system for anticancer drug screening and mutagenicity prediction, which shows how Bioclipse-R can be used to perform complex tasks from within a single software system.
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| 10. |
- Spjuth, Ola, 1977-, et al.
(författare)
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Towards interoperable and reproducible QSAR analyses : Exchange of data sets
- 2010
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Ingår i: Journal of Cheminformatics. - : BioMed Central. - 1758-2946. ; 2
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: QSAR/QSPR is a widely used method to relate chemical structures and responses based on ex- perimental observations. In QSAR, chemical structures are expressed as descriptors, which are mathematical representations like calculated properties or enumerated fragments. Many existing QSAR data sets are based on a combination of different software tools mixed with in-house developed solutions, with datasets manually assembled in spreadsheets. Currently there exists no agreed-upon definition of descriptors and no standard for exchanging data sets in QSAR, which together with numerous different descriptor implementations makes it a virtually impossible task to reproduce and validate analyses, and significantly hinders collaborations and re-use of data.RESULTS: We present a step towards standardizing QSAR analyses by defining interoperable and reproducible QSAR/QSPR data sets, comprising an open XML format (QSAR-ML) and an open extensible descriptor ontology (Blue Obelisk Descriptor Ontology). The ontology provides an extensible way of uniquely defining descriptors for use in QSAR experiments, and the exchange format supports multiple versioned implementations of these descriptors. Hence, a data set described by QSAR-ML makes its setup completely reproducible. We also provide an implementation as a set of plugins for Bioclipse that simplifies QSAR data set formation, and allows for exporting in QSAR-ML as well as traditional CSV formats. The implementation facilitates addition of new descriptor implementations, from locally installed software and remote Web services; the latter is demonstrated with REST and XMPP Web services.CONCLUSIONS: Standardized QSAR data sets opens up new ways to store, query, and exchange data for subsequent analyses. QSAR-ML supports completely reproducible dataset formation, solving the problems of defining which software components were used, their versions, and the case of multiple names for the same descriptor. This makes is easy to join, extend, combine data sets and also to work collectively. The presented Bioclipse plugins equip scientists with intuitive tools that make QSAR-ML widely available for the community.
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