Analyzing protein dynamics

Analyze a molecular dynamics simulation trajectory of the closed-to-open transition of AdK [Beckstein2009].

Molecular dynamics glossary

force field
The force field is the collection of parameters that are needed to describe the interactions between atoms in the system. Typically, it contains bonded and non-bonded terms.
frame
One time step in a trajectory is also called a “frame” as in one frame of a movie. A single frame contains one set of coordinates.
topology (file)
The topology file contains information about the atoms in the simulation: a list of atom names and numbers, the kind of atom, the bonds between atoms, and often additional information such as force field related properties (e.g., partial charges, bond strengths, Lennard-Jones parameters, ...). In the examples here we use the widely used PSF format.
trajectory (file)

A trajectory is a file that contains the positions of all atoms for a number of time steps (or frames). The positions are ordered as to correspond to the list of atoms in the topology file. Trajectory files can come in many, many different formats; each MD program produces trajectories in its own format. Examples for trajectory formats are DCD and XTC.

In order to read a trajectory, a corresponding (and matching) topology file is always needed.

File downloads

From https://becksteinlab.physics.asu.edu/pages/courses/2016/PHY542/practicals/md/files/ download

  1. the topology file adk.psf and the trajectory file adk_dims.dcd;
  2. the topology file 1ake_nowater.psf and the trajectory file 1ake_nowater.xtc.