Caught in action Interfacial and amyloid protein conformation revealed with vibrational spectroscopy

Proteins are the molecular machines of life. Shaped by billions of years of evolution, they perform tasks that vary from DNA transcription to storage of energy from sunlight to extracellular protection - with an efficiency, versatility and durability that synthetic chemists can only dream of. Various physical techniques such as X-ray crystallography and nuclear magnetic resonance spectroscopy, have helped to unravel the structure and dynamics of a large number of proteins. However, in some cases it is challenging to study proteins with conventional techniques. Notable examples are proteins active at interfaces (e.g. cell membranes or the air-water interface), and protein species (oligomers) that are crucial in the formation of amyloid structures, which are thought to be related to diseases like Alzheimer's and Parkinson's. In this thesis, we show how linear and non-linear vibrational spectroscopy (in particular: vibrational sum-frequency generation spectroscopy, one- and two-dimensional infrared spectroscopy, and vibrational spectroscopy) can shed new light on such `challenging' proteins can be investigated.