Name: Dr Philip Fowler
Institution: University of Oxford, Department of Biochemistry
Research: Ion channel simulations and free energy calculations
Dr Philip Fowler uses classical molecular dynamics to study membrane proteins, in particular the proteins that allow ions such as potassium to diffuse in and out of cells, otherwise known as ion channels. Ion channel research is extremely important, not only for its scientific interest, but also because ion channels are intimately involved in, for example, the functioning of the brain and heart.
Well-established molecular dynamics packages such as NAMD and GROMACS are used to produce simulations that can be used in either a quantitative or qualitative way.
Qualitative simulations are run by taking the structure of a protein and putting it in a more realistic environment, such as in a membrane surrounded by water and with ions added to simulate a salt solution. The results are then visualised so the structure can be looked at and sampled, providing understanding of how particular parts of the function work.
Quantitative simulations on the other hand usually produce a number that can then be compared to experimental results. How the free energy of binding changes when a potassium ion is changed to a sodium ion is one example of such a number. This can be determined experimentally and compared to the value yielded by the simulation. This free energy tells us how selective a certain ion channel is for potassium over sodium—vital for their function.
The techniques used to achieve such results are well-known and have been around for a long time but the time it takes to run them has put people off. With 34 parallel simulations taking 1-2 days each it’s not surprising. Using the NGS, 34 parallel simulations can now be run in under two weeks. With such a drastic reduction in time, researchers can run more complicated simulation scenarios such as running two mutations, checking the results by repeating simulations and running simulations backwards.
Dr Philip Fowler was a user of the NGS before it even went into production. He is now a veteran of the service, having used it for over three years, but would he recommend it to others? “No way,” he laughs. “I want it all to myself!”
This research was funded by the Wellcome Trust.
A tutorial on how to run NAMD using the Workflow Management System is available.
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