This work explores a new charge-dependent energy model consisting of van der Waals and polarization interactions between the quantum mechanical (QM) and molecular mechanical (MM) regions in a combined QMMM calculation. van der Waals interactions are commonly treated using empirical Lennard-Jones potentials, whose parameters are often chosen based on the QM atom type (e.g., based on hybridizatio...

The photoactive yellow protein (PYP) acts as a light sensor to its bacterial host: it responds to light by changing shape. After excitation by blue light, PYP undergoes several transformations, to partially unfold into its signaling state. One of the crucial steps in this photocycle is the protonation of p-coumaric acid after excitation and isomerization of this chromophore. Experimentalists st...

A hybrid quantum mechanical molecular mechanical ~QMMM! approach is used to study H3O , H2O, NH4 1 , NH3 , Cl , HCl, F, HF, CH3COO , CH3COOH, Ag 1 and glycine in both zwitterionic and nonzwitterionic forms in water. The free energies of hydration of these species are presented and are shown to compare favorably with experimental values. The difference in water– glycine interaction energy betwee...

We present QMMMW, a new program aimed at performing Quantum Mechanics/Molecular Mechanics (QM/MM) molecular dynamics. The package operates as a wrapper that patches PWscf code included in theQuantumESPRESSO distribution and LAMMPSMolecular Dynamics Simulator. It is designed with a paradigm based on three guidelines: (i) minimal amount of modifications on the parent codes, (ii) flexibility and c...

human immunodeficiency virus infection / acquired immunodeficiency syndrome (hiv/aids) is a disease pertained to the human immune system. given its crucial role in viral replication, hiv-1 protease (hiv-1 pr) is a prime therapeutic target in aids therapy. in this regard, the dynamic aspects of ligand-enzyme interactions may indicate an important role of conformational variability in hiv-1 pr in...

background: tubulin protein being the fundamental unit of microtubules is actively involved in cell division thus making them a potential anti-cancer drug target. in spite of many reported drugs against tubulin, few of them have started developing resistance in human β-tubulin due to amino acid substitutions. methods: in this study we generated three mutants (f270v, a364t and q292e) using model...

Human immunodeficiency virus infection / acquired immunodeficiency syndrome (HIV/AIDS) is a disease pertained to the human immune system. Given its crucial role in viral replication, HIV-1 protease (HIV-1 PR) is a prime therapeutic target in AIDS therapy. In this regard, the dynamic aspects of ligand-enzyme interactions may indicate an important role of conformational variability in HIV-1 PR in...

Human immunodeficiency virus infection / acquired immunodeficiency syndrome (HIV/AIDS) is a disease pertained to the human immune system. Given its crucial role in viral replication, HIV-1 protease (HIV-1 PR) is a prime therapeutic target in AIDS therapy. In this regard, the dynamic aspects of ligand-enzyme interactions may indicate an important role of conformational variability in HIV-1 PR in...