Zsuzsanna Heiner

(School of Analytical Sciences Adlershof, Humboldt-Universität zu Berlin)

Many important processes in chemistry and biology occur at interfaces where the molecular interactions and dynamics significantly differ from those observed in the bulk. Proper characterization of the behavior of peptides and proteins at macromolecular interfaces, including their reversible adsorption to surfaces and their folding into the membrane, is a prerequisite for understanding fundamental physiological processes stemming from intracellular reactions. A powerful noninvasive, optical, surface analytical tool is vibrational sum frequency generation (VSFG) spectroscopy, which often enables the direct observation of the structural and dynamical properties of interfacial molecules. Nevertheless, the acquisition times and spectral resolution of traditional broadband VSFG spectrometers are far from ideal to follow the interaction of macromolecules at bio-interfaces in real-time and in situ.
In my talk, I will provide an overview of our mid-IR light sources integrated into our unique high-resolution 100-kHz VSFG spectrometer. By employing such a spectrometer, the collection of vibrational spectra of biologically relevant macromolecules at air-solid, air-liquid, and buried interfaces has become possible at an unprecedented combination of signal-to-noise ratios, acquisition times, and spectral resolution in the spectral range of 770-3800 cm-1. I will present examples of in situ peptide and protein folding at model cell membranes, and a model system for studying protein-protein interactions.