TY - JOUR

T1 - Measuring Protein Conformation at Aqueous Interfaces with 2D Infrared Spectroscopy of Emulsions

AU - Chatterley, Adam S.

AU - Golbek, Thaddeus W.

AU - Weidner, Tobias

PY - 2022/8

Y1 - 2022/8

N2 - Determining the secondary and tertiary structures of proteins at aqueous interfaces is crucial for understanding their function, but measuring these structures selectively at the interface is challenging. Here we demonstrate that two-dimensional infrared (2D-IR) spectroscopy of protein stabilized emulsions offers a new route to measuring interfacial protein structure with high levels of detail. We prepared hexadecane/water oil-in-water emulsions stabilized by model LK peptides that are known to fold into either alpha-helix or beta-sheet conformations at hydrophobic interfaces and measured 2D-IR spectra in a transmission geometry. We saw clear spectral signatures of the peptides folding at the interface, with no detectable residue from remaining bulk peptides. Using 2D spectroscopy gives us access to correlation and dynamics data, which enables structural assignment in cases where linear spectroscopy fails. Using the emulsions allows one to study interfacial spectra with standard transmission geometry spectrometers, bringing the richness of 2D-IR to the interface with no additional optical complexity.

AB - Determining the secondary and tertiary structures of proteins at aqueous interfaces is crucial for understanding their function, but measuring these structures selectively at the interface is challenging. Here we demonstrate that two-dimensional infrared (2D-IR) spectroscopy of protein stabilized emulsions offers a new route to measuring interfacial protein structure with high levels of detail. We prepared hexadecane/water oil-in-water emulsions stabilized by model LK peptides that are known to fold into either alpha-helix or beta-sheet conformations at hydrophobic interfaces and measured 2D-IR spectra in a transmission geometry. We saw clear spectral signatures of the peptides folding at the interface, with no detectable residue from remaining bulk peptides. Using 2D spectroscopy gives us access to correlation and dynamics data, which enables structural assignment in cases where linear spectroscopy fails. Using the emulsions allows one to study interfacial spectra with standard transmission geometry spectrometers, bringing the richness of 2D-IR to the interface with no additional optical complexity.

KW - SUM-FREQUENCY GENERATION

KW - SECONDARY STRUCTURES

KW - MODEL PEPTIDES

KW - DYNAMICS

KW - ULTRAFAST

KW - ORIENTATION

KW - WATER

U2 - 10.1021/acs.jpclett.2c01324

DO - 10.1021/acs.jpclett.2c01324

M3 - Journal article

C2 - 35905449

VL - 13

SP - 7191

EP - 7196

JO - The Journal of Physical Chemistry Letters

JF - The Journal of Physical Chemistry Letters

SN - 1948-7185

IS - 31

ER -