Effects of Concentration and Surface Pressure on MBP Interaction with Cholesterol in Langmuir Films

Predicting the mechanism of MBP binding to cholesterol is meaningful in understanding how MBP participate in lateral membraneorganization. The interaction of MBP with cholesterol monolayer was investigated at three surface pressures on 10 mM Tris-HClbuffer with the different concentrations of MBP. The results show that𝜋-Aisotherms shift to larger molecular area at all pressures. Bymeans of analyzing𝜋-Tcurves, a surface pressure increase was obtained. Results indicated that the greater the protein concentrationin the subphase, the larger the increase of surface pressure. In addition, changes in monolayer surface morphology and domainformation were performed by AFM. These results provide more direct and convincing evidence for the MBP interaction withcholesterol. The MBP-cholesterol interaction suggests a significant concentrations and surface pressure dependence and is probablygoverned by hydrogen bonds. The date presented could help to understand at least one of the molecular mechanisms through whichMBP affects lateral organization of the cholesterol membrane.