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Molecular dynamics simulations of a coarse-grained, embedded-charge model of lysozyme aqueous solutions are compared with small-angle neutron scattering experiments. Measures concern different solutions with a 10% by weight protein concentration and an increasing pH in the range 2–6. The model is based on a soft-core modification of the original Carlsson–Malmsten–Linse model, where in particular all residues carrying an appreciable amount of residual charge, as a function of the pH, are explicitly taken into account in the overall macromolecular interaction. Simulations reproduce qualitatively the experimental trend of the structure factor such as, in particular, the observed change from a low-pH regime, dominated by repulsive interactions, to behaviour mainly determined by attractive forces, at higher pH. Possible improvements of the model, towards a better reproduction of the structural properties of the real solution, are proposed.

We have investigated the dimyristoylphosphatidylcholine system with a high concentration of butanol (two molecules per phospholipid) via X-ray diffraction, differential scanning calorimetry and density measurements. A lowering of the main transition temperature for the membrane/alcohol system has been observed. The phospholipid bilayer/alcohol system is characterised by a higher density value than the pure membrane, as determined by volumetric measurements. Analysis of diffraction patterns has shown the existence of a more packed structure due to the presence of alcohol. The area of polar head has also been estimated.