We present a method that adapts the parameters describing the surface dynamics of an epitaxial system to a set of experimental intensities of He scattering at thermal energies. The method is applied to the problem of Ag growth on a Pt(111) surface at temperatures between 250 and 600K.

A theoretical study of 1,3-benzenedimethanethiol adsorption on Au(111) planar surface at low coverage is conducted. Several configurations were taken into consideration but all of them had both sulphur atoms deprived of the terminal H atom. Also, the case of gold surface reconstruction was examined and results are reported for a configuration analogous to one proposed for methylthiolate adsorption that has lately gained much consensus, one in which both sulphur atoms are coordinated to a single gold adatom.

The photosynthetic reaction center (RC) is an integral membrane protein that, upon absorption of photons, generates a hole-electron couple with a yield close to one. This energetic state has numerous possible applications in several biotechnological fields given that its lifetime is long enough to allow non-metabolic ancillary redox chemistry to take place. Here we focus on RCs reconstituted in liposomes, formed with sole phospholipids or in blends with other lipids, and show that the electrical charge sitting on the polar head of such hydrophobic molecules does play an important role on the stability of the hole-electron couple. More specifically this study shows that the presence of negative charges in the surrounding of the protein stabilizes the charge-separated state while positive charges have a strong opposite effect.

The computational platform ENVIRONMENT, developed to simulate stochastically reaction systems in varying compartmentalized conditions [Mavelli and Ruiz-Mirazo: Philos Trans R Soc Lond B Biol Sci 362:1789-1802, 2007; Physical Biology 7(3): 036002, 2010], is here applied to study the dynamic properties and stability of model protocells that start producing their own lipid molecules (e.g., phospholipids), which get inserted in previously self-assembled vesicles, made of precursor amphiphiles (e.g., fatty acids). Attention is mainly focused on the changes that this may provoke in the permeability of the compartment, as well as in its eventual osmotic robustness.

Liposomes represent a versatile biomimetic environment for studying the interaction between integral membrane proteins and hydrophobic ligands. In this paper, the quinone binding to the Q(B)-site of the photosynthetic reaction centers (RC) from Rhodobacter sphaeroides has been investigated in liposomes prepared with either the zwitterionic phosphatidylcholine (PC) or the negatively charged phosphatidylglycerol (PG) to highlight the role of the different phospholipid polar heads. Quinone binding (K (Q)) and interquinone electron transfer (L (AB)) equilibrium constants in the two type of liposomes were obtained by charge recombination reaction of Q(B)-depleted RC in the presence of increasing amounts of ubiquinone-10 over the temperature interval 6-35 A degrees C. The kinetic of the charge recombination reactions has been fitted by numerically solving the ordinary differential equations set associated with a detailed kinetic scheme involving electron transfer reactions coupled with quinone release and uptake. The entire set of traces at each temperature was accurately fitted using the sole quinone release constants (both in a neutral and a charge separated state) as adjustable parameters. The temperature dependence of the quinone exchange rate at the Q(B)-site was, hence, obtained. It was found that the quinone exchange regime was always fast for PC while it switched from slow to fast in PG as the temperature rose above 20 A degrees C. A new method was introduced in this paper for the evaluation of constant K (Q) using the area underneath the charge recombination traces as the indicator of the amount of quinone bound to the Q(B)-site.