Jeffry Madura

The ability of antifreeze proteins (AFP's) and glycoproteins (AFGP's) to prevent damage to certain organisms under cold stress is well established. These molecules have also been shown to prevent chilling damage in some biological membranes and interaction between membranes and AF(G)P's has been observed during chilling events; however, the exact mechanism of membrane stabilization is still not well understood. Molecular modelling is an ideal technique for probing atomistic information in these systems although modelling studies to date have focused on peptide structure and the site and mode, e.g., insertion, of the peptide-membrane interaction. To provide insight into how AF(G)P's may act to stabilize (or destabilize) membranes during phase transitions, we have conducted molecular dynamics (MD) simulations of a solvated dimyristoylphosphatidylcholine (DMPC) lipid bilayer containing an AFP Type I …

The principal components of the 13C chemical shift tensors for the ten crystallographically distinct carbon atoms of the active pharmaceutical ingredient cimetidine Form A have been measured using the FIREMAT technique. Density functional theory (DFT) calculations of 13C and 15N magnetic shielding tensors are used to assign the 13C and 15N peaks. DFT calculations were performed on cimetidine and a training set of organic crystals using both plane-wave and cluster-based approaches. The former set of calculations allowed several structural refinement strategies to be employed, including calculations utilizing a dispersion-corrected force field that was parametrized using 13C and 15N magnetic shielding tensors. The latter set of calculations featured the use of resource-intensive hybrid-DFT methods for the calculation of magnetic shielding tensors. Calculations on structures refined using the new force-field …