Biophysical Society Thematic Meeting - October 13-15, 2015

Biophysics of Proteins at Surfaces: Assembly, Activation, Signaling

Thursday Speaker Abstracts

Protein Structural Dynamics at Surfaces as Studied by Infrared Nanospectroscopy Joachim Heberle . Freie Universität, Berlin, Germany. Membrane proteins are the target of more than 50% of all drugs and are encoded by about 30% of the human genome. Electrophysiological techniques, like patch-clamp, unravelled many functional aspects of membrane proteins but suffer from structural sensitivity. We have developed Surface Enhanced Infrared Absorption Spectroscopy (SEIRAS) to probe the structure and function of solid-supported biomembranes and membrane proteins on the level of a monolayer. In a new approach, we monitored the expression, insertion and folding of membrane proteins by SEIRAS. A cell-free assay to express bacteriorhodopsin (bR) was used and insertion and folding of the nascent polypeptide into surface-tethered lipidic nanodiscs was followed in- situ and time-resolved by SEIRAS to resolve this complex reaction via the analysis of the amide I vibration of the peptide backbone (C=O stretching vibration). The structure of the native environment of bR in the purple membrane was probed by scanning near-field IR microscopy. Mapping of the protein structure with 30 nm spatial resolution and sensitivity to individual protein complexes by Fourier transform infrared nano-spectroscopy (nano-FTIR) was demonstrated. The first broadband infrared spectra of purple membranes were recorded indicating their local α-helical structure.

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