FTIR studies on secondary structures of fibrous proteins: Amide III

Folding defects of fibrous proteins are involved in many genetic pathologies, such as fibrosis, Alzheimer's and Creutzfeldt-Jakob Disease. In particular, type I collagen is the most abundant fibrous-collagen protein in human, playing an important role in mammalian tissues. Its secondary structure needs to be extensively studied as anomalous organizations of collagen networks are detected to be involved in several pathologies.

Fourier Transformed Infrared Spectroscopy (FTIR) is a useful tool to investigate protein secondary structures, although analysis of Amide I e Amide II can be affected by overlapping with water absorption and some amino acid side chain bands, respectively.
FTIR has been used to study the Amide III band for structural analysis of fibrous proteins. The investigation allowed a better assignment of the components of Amide III band of a typical fibrous protein, such as type I collagen, to its characteristic secondary structure. The result showed that studies of Amide III can be exploited for its sensitivity for protein structural analysis, overcoming the limitations imposed by water absorption to Amide I.

Facility: SISSI Beamline.

Bibliography: C. Stani et al., “FTIR investigation of the secondary structure of type I collagen: New insight into the amide III band”, Spectrochim. Acta A Mol. Biomol. Spectrosc., 2020, 229, 118006. DOI: 10.1016/j.saa.2019.118006

Illustration by David S. Goodsell and the RCSB PDB, under CC-BY-4.0 license.