Effects of surface pressure in the relaxation processes in the adsorption of proteins to lipid membranes

HOLLMANN, AXEL; DELFEDERICO, LUCRECIA; DE ANTONI, GRACIELA; SEMORILE, LILIANA; DISALVO, ANIBAL

Salta, Argetnina

Congreso; 3rd Latin American Protein Society Meeting; 2010

Sociedad Argentina de Biofisica, Latin American Protein Society

The aim of the present work was to evaluate the kinetics of the interaction of an aqueous soluble protein, S-layer protein from Lactobacillus brevis, with phosphatidylcholine monolayers in which the surface pressure was modified by changing the surface charge and the cholesterol ratio. The increase in the chain packing either by the addition of cholesterol or by reducing the surface charge repulsion have a similar effect than increasing the surface pressure by lateral compression. In all cases, an anomalous diffusion process, representative of a relaxation process due to lipid heterogeneity is involved in protein adsorption. At low pressures, turns into a fickian one denoting that membrane tension disappears in packed membranes. Several interesting points can be derived from these observations. In first place, they denote that the less packed states are more versatile in terms of structural response to protein attachment. As the less packed monolayers are more hydrated, the relaxation processes at low initial surface pressures could be connected by the structural changes in water layers attached to the lipid in the outer hydration shell.