Protein secondary structure signatures from energy loss spectra recorded in the electron microscope

Katia March, Kartik Venkatraman, Chloe Du Truong, Dewight Williams, Po Lin Chiu, Peter Rez

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish (US)
JournalJournal of Microscopy
DOIs
StateAccepted/In press - 2020

Keywords

  • FTIR
  • HR-EELS
  • nanoscale
  • polarisation
  • protein secondary structure

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Histology

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