Protein/lipid interactions in phospholipid monolayers containing the bacterial antenna protein B800–850

Determination of the physical structure of biological materials at biosensor interfaces by techniques of increasing magnification from microscopic to molecular scale

“…After the monolayer was compressed to a pressure of approximately 5 rnN.m-', the proteinj50 pL of aqueous solution at a concentration of lo-" M) and, if desired for aggregation studies, the dextran solution ( lop2 M) were spread on the fluid monolayer surface by using a syringe as described previously (Heckl et al, 1985). Monolayers containing lipid and ConA-dextran complex were transferred onto glass slides by the typical Langmuir-Blodgett dipping technique for study by electron microscopy.…”

“…Mixtures of DPPC and dye containing 1 mol % of the latter in 3:l viv chloroformimethanol mixed solvent were spread on the surface of the water containing M Mn2+ and Ca2+ and studied with the equipment described by Losche and Mohwald (1984). After the monolayer was compressed to a pressure of approximately 5 rnN.m-', the proteinj50 pL of aqueous solution at a concentration of lo-" M) and, if desired for aggregation studies, the dextran solution ( lop2 M) were spread on the fluid monolayer surface by using a syringe as described previously (Heckl et al, 1985). Monolayers containing lipid and ConA-dextran complex were transferred onto glass slides by the typical Langmuir-Blodgett dipping technique for study by electron microscopy.…”

Effect of the polar headgroup of phospholipids on their interaction with actin

“…3B, curves 2-5). A decrease of the critical surface pressure of DMPE associated with F-actin suggests that electrostatic interactions prevail between the lipid and the protein [27]. Finally, we note that an important broadening of the transition is observed as the concentration of the protein in the subphase is increased with both G-and F-actin.…”

“…An increase of the critical surface pressure as a function of the concentration of the protein in the subphase indicates that the protein acts as an impurity, just competing as a surfactant at the air-water interface without specific interaction with the phospholipids, as previously observed with other systems [24][25][26]. On the contrary, a decrease of the critical surface pressure indicates that electrostatic interactions prevail between the lipids and the protein molecules [17,27]. Fig.…”

“…If the protein increases the surface pressure (so-called the critical surface pressure) at which this transition occurs, the protein just competes with the lipid molecules at the interface, without interaction [24][25][26]. On the contrary, if the protein decreases the critical surface pressure, it indicates electrostatic interactions between lipids and protein [17,27].…”