Surface-specific spectroscopy of lipids and proteins

A substantial fraction of biomolecular processes occurs at interfaces. Interactions of proteins with lipid membranes at the membrane/water interface present a critical example. Understanding these interactions enables us to unravel the origin of diseases, develop effective drugs, reveal principles for biomimetic material design, and, in general, understand bases of life. However, the immense complexity of a cell and, all the more, of living organisms overcomplicates interpretation of observed effects. At the same time, to get insight into vital (sub)cellular processes, molecular-scale information on the organization of lipids and proteins and their interactions is necessary. For this reason, simple models are helpful to employ. For instance, (sub)cellular biomembrane has been represented by a lipid bilayer, vesicle, or monolayer. In this thesis, we focus on the characterization of biomolecular organization at bio-interfaces and use lipid monolayer to mimic a biomembrane. To probe interfacial molecules, we employ a combination of surface-specific spectroscopic and microscopic techniques. We complement surface-specific studies by information obtained with bulk techniques. Additionally, we pay particular attention to the organization of water at bio-interfaces inspired by the fact that interactions of water with other biomolecules are crucial for cell life and functions. A combination of bulk and interfacial studies allows us to investigate how properties of interface affect protein interfacial adsorption and folding. The powerful experimental toolbox implemented in this thesis suggests a platform to study various aspects of protein and lipid solvation, lipid packing in biomembranes, lipid-protein interactions, and organization and functional roles of water in mediating these interactions.