Characterization of protein secondary structures at interfaces in situ and in real time is important to understand biotic-abiotic interactions and develop biometerials and biosensors. However, such characterization remains challenging because it requires techniques that are both selective to interfaces and secondary structures. Here, we demonstrate that chiral sum frequency generation spectroscopy (cSFG) can provide peptide amide I and N-H stretch vibrational signals that are free of water background and characteristic to parallel beta-sheet, anti-parallel beta-sheet, alpha-helix, 3-10 helix and random coil. This enables cSFG to indentify protein secondary structures at interfaces. Using cSFG, we observed misfolding of an amyloid protein from disordered structures to alpha-helices and then converting to beta-sheets upon interactions with lipid molecules at the air/water interface in situ and in real time. Our results reveal that cSFG can be used to characterize secondary structures at interfaces to address fundamental and engineering problems related to biotic-abiotic interfaces.

Characterization of protein secondary structures at interfaces using chiral sum frequency generation spectroscopy

244th National Meeting (2012)

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