Personal profile

Research overview

The interface between biology and chemistry is fertile ground for the development of new computational techniques. Yet it is still hard to predict protein-ligand binding, model protein folding or design effective pharmaceutical products.

Enzyme-catalysed reactions are ubiquitous and essential to the chemistry of life. Structures, gene sequences, mechanisms, metabolic pathways and kinetic data are currently spread between many different databases and throughout the literature. We have created MACiE, the world's first comprehensive electronic database of the chemical mechanisms of enzymatic reactions. We are using MACIE to investigate fundamental questions about the chemistry of enzyme functions, their evolution, and their substrate specificity. 

Improving the prediction of solubility is essential to reduce the current unacceptable attrition rate in drug development. We are developing methods to predict aqueous solubility for drug-like molecules, and hope to move on to study its dependence on pH, salt effects and crystal polymorphism. We have developed a number of predictive methods for solubility, of which the most successful is based on a Random Forest of decision trees. We are also using computational chemistry to calculate the various energy terms associated with solvation. This work spans quantum chemistry, molecular simulation, QSAR and chemical informatics.

Additional information about the current Mitchell Group can be found here: http://chemistry.st-andrews.ac.uk/staff/jbom/group/

Research interests

Enzyme Catalysis: Enzyme-catalysed reactions are ubiquitous and essential to the chemistry of life. Structures, gene sequences, mechanisms, metabolic pathways and kinetic data are currently spread between many different databases and throughout the literature. We have created MACiE, the world's first comprehensive electronic database of the chemical mechanisms of enzymatic reactions. We are now using MACiE to investigate fundamental questions about the chemistry of enzyme functions, their evolution, and their substrate specificity.
Computing Solubility and Bioavailability: Improving the prediction of solubility is essential to reduce the current unacceptable attrition rate in drug development. We have developed methods to predict solubility for drug-like molecules, with particular reference to dependence on pH, salt effects and crystal polymorphism. We tested a number of predictive methods, including Multi-Linear Regression, Random Forest and Support Vector Machines. This work spans traditional quantum chemistry, molecular simulation, QSAR and chemical informatics. The combination of models for protein target prediction with large databases containing toxicological information for individual molecules allows the derivation of “toxiclogical” profiles, i.e., to what extent are molecules of known toxicity predicted to interact with a set of protein targets. To predict protein targets of drug-like and toxic molecules, we have built a computational multiclass model using the Winnow algorithm based on a dataset of known protein targets.  
Computational Toxicology: We are working on the development of in silico techniques for the prediction of toxicological properties and, more broadly, the elucidation of the mechanisms of action of toxic substances. It is hoped that a better understanding of the causal factors pertaining to toxicity will yield greater predictive insight as well. We currently have a project entitled "Machine Learning Methods for Predicting Phospholipidosis". We are using a variety of Machine Learning Methods, including Random Forest and a novel Genetic Algorithm. Phospholipidosis can be characterised by the accumulation of phospholipids in the lysosomes of many cell types. It may be induced by certain drugs of which the most common are cationic amphiphilic drugs.
Protein-ligand Binding Affinities: We have recently used the Random Forest machine learning method to generate a scoring function. Unlike other knowledge-based functions, it makes no assumptions about the mathematical form of the relationship between observed frequencies of contacts and their contributions to the binding free energy. Our method also allows known binding affinities to contribute to the learning process.

Future research

* Modelling the evolution of enzyme catalysis.
* Theoretical computation of solubility and improved understanding of hydrophobicity.
* Predictive computational models for toxicology.
* Protein target prediction for drugs in sport.
* Machine learning approaches to predict enzyme function.

Industrial relevance

Much of our work on predicting bioavailability and solubility is of particular interest to the pharma industry, but also is especially relevant to the fields of food science and nutrition. In recent years, we have moved into computational toxicology, a field of wide-ranging industrial and commercial importance, especially with the advent of REACH legislation. Our work on enzyme reactions has applications in  designing better, and indeed novel, enzyme-based systems, from laundry to biofuels to deodorants.
We are building some public domain toxicology and bioavailability models, designed to be openly available to SMEs and non-profit organisations, as well as academics.

Biography

John Mitchell has a PhD in Theoretical Chemistry from Cambridge. He returned there from University College London in 2000, taking up a lectureship in Chemistry. He was appointed to a readership at St Andrews in 2009. His recent research has used computational techniques in pharmaceutical chemistry and structural bioinformatics. His group have worked extensively on prediction of bioactivity, solubility, melting point and hydrophobicity from chemical structure, using both informatics and theoretical chemistry methodologies. Recently they have developed novel applications of machine learning in computational biochemistry, such as drug side effect prediction, and identifying athletic performance enhancers.

Profile Keywords

Machine Learning, Artificial Intelligence & informatics in Chemistry; Prediction of solubility and other molecular thermodynamic properties; Modelling the organic crystalline state; Classification and computer-based representation of enzyme reaction mechanisms; Bioinformatics studies of molecular evolution; Modelling protein-ligand interactions.

Teaching activity

Lecturer CH5714 Chemical Applications of Electronic Structure Calculations; Lecturer CH4431 Scientific Writing; Lecturer CH3717 Statistical Mechanics and Computational Chemistry; Convenor & Tutor, CH1202 Introductory Chemistry; Lecturer ID1003 Great Ideas 1; Lecturer ID1004 Great Ideas 2; Tutor CH2701 Physical Chemistry 2; Tutor CH1401 Introductory Inorganic and Physical Chemistry; Lecturer SUPACCH Computational Chemistry (Postgraduate course).

Expertise related to UN Sustainable Development Goals

In 2015, UN member states agreed to 17 global Sustainable Development Goals (SDGs) to end poverty, protect the planet and ensure prosperity for all. This person’s work contributes towards the following SDG(s):

  • SDG 3 - Good Health and Well-being

Education/Academic qualification

Doctor of Philosophy, Theoretical Studies of Hydrogen Bonding, University of Cambridge

1 Oct 198730 Sept 1990

Award Date: 2 Feb 1991

Keywords

  • QD Chemistry
  • solubility
  • computational chemistry
  • chemoinformatics
  • bioinformatics

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