SPECIFIC INTERACTIONS OF PROTEINS WITH FUNCTIONAL LIPID MONOLAYERS - WAYS OF SIMULATING BIOMEMBRANE PROCESSES

The interplay between molecular self-organization and molecular recognition leads to the construction of functional supramolecular systems in which order and mobility are combined and whose function is based on their organization. These fascinating phenomena, for which the living cell is a perfect example, can be understood only if a wide range of scientific disciplines work together. For this purpose, synthetic supramolecular systems can be used to simulate natural biomembrane processes. One example of this is the specific recognition and interaction between membrane-bound ligands and receptor proteins. Thus, the specific interaction of vitamin H (biotin) with the tetrafunctional protein streptavidin in the monolayer leads to 2D crystallization of the protein. Structural analysis shows that the protein is attached to the lipid membrane by two biotin-binding sites, leaving two still free. The opportunity this allows for biotinylated molecules to dock to the protein leads to interesting possibilities for constructing protein-containing functional multilayers. Another example for the simulation of biomembrane processes is the function of enzymes which is coupled to the recognition process. In the interaction of phospholipase A2 with lecithin monolayers, specific recognition between enzyme and substrate is followed by an active phase of lipid cleavage and then by aggregation of the enzyme to give domains of regular morphology. Fluorescence microscopy can be used to follow this process directly: an enzyme caught in action.