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Thermodynamic Cycles

Definition
Definition
Definition

Thermodynamic cycles are conceptual tools used in computational chemistry and drug discovery to relate different states of a molecular system through a series of reversible steps. The different states are part of a closed cycle where the total free energy change around it amounts to zero. When the energy differences within a cycle is known, the unknown energy difference can be derived. This allows the calculation of free energy differences (e.g., binding, solvation, or mutation energies) using e.g. molecular dynamics or quantum mechanics. These cycles underpin rigorous approaches like free energy perturbation (FEP) and thermodynamic integration (TI).

Importance in Computational Drug Discovery:

  • Enable accurate prediction of binding affinities, solvation energies, and mutation effects by leveraging well-defined reference states.
  • Provide a framework for rigorous comparison of computational and experimental free energy data.
  • Support lead optimization by quantifying the energetic impact of chemical modifications or mutations.
  • Facilitate the design of alchemical transformations for relative binding free energy calculations.
  • Integrate with enhanced sampling and molecular simulation methods to improve reliability and reproducibility of predictions.

Key Tools

  • AMBER: Provides robust support for free energy calculations using thermodynamic cycles (FEP, TI).
  • GROMACS: Widely used for molecular simulations and free energy calculations via thermodynamic cycles.
  • FEP+ (Schrödinger): Specialized for accurate relative binding free energy predictions using thermodynamic cycles.
  • NAMD: Supports alchemical free energy calculations and thermodynamic integration.

Literature

"Thermodynamics and Kinetics of Drug-Target Binding by Molecular Simulation"

  • Publication Date: 2020
  • DOI: 10.1021/acs.chemrev.0c00534
  • Summary: This comprehensive review discusses the application of molecular simulations to study the thermodynamics and kinetics of drug-target interactions. It emphasizes the use of thermodynamic cycles in calculating binding free energies and provides insights into the methodologies and challenges associated with these calculations.

"Predicting Intrinsic Aqueous Solubility by a Thermodynamic Cycle"

  • Publication Date: 2008
  • DOI: 10.1021/mp7000878
  • Summary: This study presents methods to predict the intrinsic aqueous solubility of crystalline organic molecules using thermodynamic cycles. It combines computational calculations with informatics approaches to improve solubility predictions, which are crucial in drug development.

"Precise Binding Free Energy Calculations Unlock New Frontiers in Drug Discovery"

  • Publication Date: 2025
  • DOI: 10.1021/acs.jcim.5c00193
  • Summary: This article introduces the PairMap method, which incorporates well-constructed intermediates and thermodynamic cycles to achieve high-precision binding free energy predictions. The approach enhances the accuracy of computational drug design and accelerates the discovery of effective therapeutics.

"Thermodynamic Cycle Integration by Computer Simulation as a Tool for Obtaining Free Energy Differences in Molecular Chemistry"

  • Publication Date: 1987
  • DOI: 10.1007/BF01676960
  • Summary: This seminal paper discusses the use of thermodynamic cycle integration in computer simulations to calculate free energy differences. It lays the groundwork for modern computational techniques employed in drug discovery and molecular chemistry.

"Ligand Binding Thermodynamic Cycles: Hysteresis, the Locally Perturbed Conformer, and the Role of Conformational Entropy"

  • Publication Date: 2019
  • DOI: 10.1021/acs.jctc.9b00740
  • Summary: This study analyzes closed thermodynamic cycles involving congeneric ligands binding to HIV-1 integrase. It explores the concepts of hysteresis and conformational entropy, providing insights into the thermodynamic aspects of ligand binding and drug design.