Cholesterol inhibits oxygen permeation through biological membranes: mechanism against double-bond peroxidation.

The presence of oxygen molecules (O) in biological membranes promotes lipid peroxidation of phospholipids with unsaturated acyl chains. On the other hand, cholesterol is considered to be an antioxidant molecule as it has a significant barrier effect on the permeation of O across membranes. However, a comprehensive explanation of how cholesterol affects the distribution and diffusion of O within lipid bilayers is yet to be established.

Unraveling the interaction between singlet state atomic oxygen O(D) and water: toward the formation of oxywater and hydrogen peroxide.

We performed high-level quantum mechanical calculations to explore the interaction of atomic oxygen in the ground triplet state, O(P), and the excited singlet state, O(D), with water. We reported the potential energy curves for a few lowest electronic states when an atomic oxygen approaches the oxygen of a water molecule. Our results predict the formation of a singlet oxywater species as the product of O(D) and HO which lies about 149.

Effect of oxidation on POPC lipid bilayers: anionic carboxyl group plays a major role.

Phospholipids with unsaturated acyl chains are major targets of reactive oxygen species leading to formation of oxidized lipids. Oxidized phospholipids have a pronounced role in cell membrane damage. We investigated the effect of oxidation on physiological properties of phospholipid bilayers using atomistic molecular dynamics simulations.

Getting excited: challenges in quantum-classical studies of excitons in polymeric systems.

A combination of classical molecular dynamics (MM/MD) and quantum chemical calculations based on the density functional theory (DFT) was performed to describe the conformational properties of diphenylethyne (DPE), methylated-DPE and poly para phenylene ethynylene (PPE). DFT calculations were employed to improve and develop force field parameters for MM/MD simulations. Many-body Green's function theory within the GW approximation and the Bethe-Salpeter (GW-BSE) equation were utilized to describe the excited states of the systems.