Force Measurements on Myelin Basic Protein Adsorbed to Mica and Lipid Bilayer Surfaces Done with the Atomic Force Microscope

The mechanical and adhesion properties of myelin basic protein (MBP) are important for its function, namely the compaction of the myelin sheath. To get more information about these properties we used atomic force microscopy to study tip-sample interaction of mica and mixed dioleoylphosphatidylserine (DOPS) (20%)/egg phosphatidylcholine (EPC) (80%) lipid bilayer surfaces in the absence and presence of bovine MBP. On mica or DOPS/EPC bilayers a short-range repulsive force (decay length 1.0-1.3 nm) was observed during the approach. The presence of MBP always led to an attractive force between tip and sample. When retracting the tip again, force curves on mica and on lipid layers were different…