FTIR protein secondary structure analysis of human ascending aortic tissues

Abstract

Journal of BIOPHOTONICSThe advent of moderate dilatations in ascending aortas is often accompanied by structural modifications of the main components of the aortic tissue, elastin and collagen. In this study, we have undertaken an approach based on FTIR microscopy coupled to a curve-fitting procedure to analyze secondary structure modifications in these proteins in human normal and pathological aortic tissues. We found that the outcome of the aortic pathology is strongly influenced by these proteins, which are abundant in the media of the aortic wall, and that the advent of an aortic dilatation is generally accompanied by a decrease of parallel b-sheet structures. Elastin, essentially composed of b-sheet structures, seems to be directly related to these changes and therefore indicative of the elastic alteration of the aortic wall. Conventional microscopy and confocal fluorescence microscopy were used to compare FTIR microscopy results with the organization of the elastic fibers present in the tissues. This in-vitro study on 6 patients (three normal and three pathologic), suggests that such a spectroscopic marker, specific to aneurismal tissue characterization, could be important information for surgeons who face the dilemma of moderate aortic tissue dilatation of the ascending aortas.Infrared spectroscopy and imaging was applied to analyse Human thoracic ascending aortas with the aim to highlight the protein secondary structure reorganisation after an aneurism outcome. We used a curve-fitting procedure to visualise modifications in the protein spectral profile where alteration of b structures in pathological aortas could be detected. Our spectroscopic observations on tissue sections corroborated with confocal fluorescence microscopy clearly demonstrating that elastic fibres of aortic wall are strongly altered. Elastin appears as the privileged target during the pathological process.

Fourier transform infrared spectroscopy to quantify collagen and elastin in an in vitro model of extracellular matrix degradation in aorta

“…3-B,D). This slight shift may be explained by the differences in secondary structures of collagen and elastin 29,31,57 . Collagen is composed mainly of α-helical structures, while elastin is primarily β-sheets; the amide I band of α-helical structures occurs between 1643–1667 cm −1 , and for β-sheet structures occurs between 1610–1645 cm −1 29,57 .…”

“…These investigators demonstrated that normal and aneurysmal human arterial tissue biopsies could be differentiated using the ratio of α-helical to β-sheet structures and principal component analysis (PCA) 29 , hierarchical cluster analysis (HCA) 30 and factorial discriminant analysis (FDA) 32 . Furthermore, curve-fitting was applied to the spectra to detect alteration of β structures in the protein spectral profile of pathological aortas 31 . Although this group of studies set the ground work for differentiation of aneurismal from healthy aortic tissues, there has been minimal confirmation with histology or biochemical analysis, and the relative degradation of the primary ECM components (elastin and collagen) associated with aneurysm condition has not been specifically evaluated.…”

Antioxidant and antimicrobial properties of essential oils encapsulated in zein nanoparticles prepared by liquid–liquid dispersion method

“…FTIR provides information of secondary structures of proteins (Bonnier et al, 2008) and also is used for EOs analysis (Vera & Chane-Ming, 1999). Only the treatments under neutral pH are presented because different pH conditions had no effect on FTIR results.…”

Influence of the architecture on the molecular mobility of synthetic fragments inspired from human tropoelastin

“…Some distinct features can be observed between S4 peptides and S4 fibers on these global spectra; in peculiar the amide I band located at 1645 cm -1 in S4 peptides is narrower and shifted at 1627 cm -1 in S4 fibers. Since the amide I-II region consists of several bands strongly dependent on secondary conformations, it was subjected to curve fitting in order to resolve the various underlying and overlapping spectral features that contribute to this complex region [8][9][10][11]. The decomposed FTIR spectra of the amide I-II region are superimposed on global spectra in Figure 2 and the assignments of the vibrational bands are reported in Table1.…”