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Protein secondary structure signatures from energy loss spectra recorded in the electron microscope
Author(s) -
March Katia,
Venkatraman Kartik,
Truong Chloe Du,
Williams Dewight,
Chiu PoLin,
Rez Peter
Publication year - 2021
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/jmi.12995
Subject(s) - infrared spectroscopy , infrared , spectroscopy , protein secondary structure , resolution (logic) , chemistry , fourier transform infrared spectroscopy , bacteriorhodopsin , spectral line , analytical chemistry (journal) , crystallography , materials science , optics , physics , biochemistry , organic chemistry , chromatography , quantum mechanics , astronomy , artificial intelligence , membrane , computer science
Infrared spectroscopy is a powerful technique for characterising protein structure. It is now possible to record energy losses corresponding to the infrared region in the electron microscope and to avoid damage by positioning the probe in the region adjacent to the structure being studied. Spectra from bacteriorhodopsin, a protein that is predominately a α helix, and OmpF porin, a protein that is mainly β sheet show significant differences over a spectral range from ∼0.1 to 0.25 eV (∼1000 to 1800 cm –1 ). Although the energy resolution equivalent to 60 cm –1 is inferior to Fourier Transform InfraRed Spectroscopy (FTIR) the spectra are very sensitive to molecular orientation. Polar bonds aligned parallel to the specimen grid make particularly strong contributions to the energy loss spectra. Ultra‐high‐resolution energy loss spectroscopy in the electron microscope can potentially add useful information to imaging and diffraction for determining the secondary structure misfolding believed to be responsible for dementia diseases such as Alzheimer's.