NMSim

NMSim simulates large-scale protein conformational changes by combining coarse-graining with FIRST, rigid-cluster normal-mode analysis, and constrained geometric simulations to model backbone and side-chain motions for structural and functional interpretation.

Key Features:

• Coarse-Graining: The protein structure is coarse-grained using the FIRST software to simplify atomistic detail while retaining essential conformational information.
• Rigid-Cluster Normal-Mode Analysis: A rigid-cluster normal-mode analysis identifies low-frequency normal modes that capture large-scale protein motions.
• Constrained Geometric Simulations: Normal modes guide backbone motions through constrained geometric simulations while side chains are biased toward favorable rotamer states to produce physically plausible conformations.
• Simulation Types: Supports unbiased exploration, targeted simulation of specific regions or interactions, and constrained geometric simulations to explore structural hypotheses or functional states.
• Iterative Correction: Generated structures undergo repeated cycles of simulation, validation, and adjustment to refine accuracy and consistency with experimental data.

Scientific Applications:

• Structural Biology: Models conformational changes and dynamics to interpret protein function and mechanisms.
• Drug Discovery: Explores conformational ensembles and refines binding-site conformations to support the design of targeted therapeutics.
• Molecular Modeling: Predicts protein structures and analyzes conformational variability at the atomic level.

Methodology:

Coarse-graining of the protein structure is performed using FIRST; rigid-cluster normal-mode analysis identifies low-frequency modes; constrained geometric simulations use those modes to guide backbone motions while biasing side chains toward favorable rotamer states; simulations can be executed as unbiased exploration, targeted simulation, or constrained geometric simulations; generated structures are iteratively corrected by repeated cycles of simulation, validation, and adjustment.