Here we model the nucleophilic attack by Asp333 at each of the two epoxide carbon atoms in t-SO and t-DPPO in multiple QM/MM (AM1/CHARMM22) umbrella sampling MD simulations.
These comprise sophisticated simulation technique like REMD (14, 15), umbrella sampling (16, 17), transition path sampling (18), the Markovian state model (19), and the metadynamics method (20, 21).
Representations of restraints and advanced sampling methods (e.g. replica-exchange, umbrella sampling) were also missing.
These methods usually involve the creation of multiple ensembles or replica that can be run in parallel (e.g. temperature replica-exchange, umbrella sampling).
However, VAUS and regular adaptive umbrella sampling (AUS) methods are yet computationally expensive.
Virtual-system coupled adaptive umbrella sampling (VAUS) enhances sampling along a reaction coordinate by using a virtual degree of freedom.
The free-energy profile for the position of the syb2 membrane anchor in the membrane was determined using umbrella sampling.
Some of their specific examples such as replica-exchange molecular dynamics and replica-exchange umbrella sampling are described in detail.
We demonstrate the feasibility of using "umbrella sampling" to do Monte Carlo Markov-sampling runs each covering a substantial range of density: "density-scaling Monte Carlo," or DSMC.
One attractive approach to meet both daunting tasks is Born Oppenheimer ab initio QM/MM molecular dynamics (aiQM/MM-MD) simulation with umbrella sampling.
