Investigating Molecular Kinetics by Variationally Optimized Diffusion Maps | JoVE Visualize

Area of Science:

Theoretical Molecular Dynamics
Computational Biophysics
Chemical Physics

Background:

Identifying reaction coordinates for rare molecular events like protein folding is a significant challenge in theoretical molecular sciences.
Diffusion Map coordinates (DCs) approximate true reaction coordinates but lack dynamical information, hindering validation and rate constant computation.
Existing methods struggle to accurately parameterize and validate these coordinates using dynamical information.

Purpose of the Study:

To integrate the Diffusion Map approach with the Variational Approach for Conformation Dynamics (VAC) for improved molecular transition analysis.
To validate the quality of Diffusion Map coordinates and enable the computation of system relaxation rate constants.
To evaluate different metric spaces for enhanced performance in analyzing molecular dynamics.

Main Methods:

Combined Diffusion Map approach with the Variational Approach for Conformation Dynamics (VAC).
Utilized Diffusion Map coordinates as a basis set, optimized via VAC using time-correlation information from molecular dynamics (MD) trajectories.
Applied the integrated approach to ultra-long MD simulations of the Fip35 WW domain and evaluated metric space performance.

Main Results:

The first Diffusion Map coordinates provide a good approximation to true reaction coordinates but can be further refined using VAC.
The combined approach yields excellent approximations for system relaxation rates.
Kinetic maps based on time-lagged independent component analysis outperform pairwise minimal root-mean-square deviation in metric space evaluation.

Conclusions:

The integration of Diffusion Maps and VAC offers a powerful framework for analyzing complex molecular transitions and rare events.
This method significantly improves the accuracy of reaction coordinates and enables reliable computation of relaxation dynamics.
The findings highlight the importance of dynamically informed coordinates and effective metric spaces for advancing molecular simulations.