| 1. |
- Baldassarre, Maurizio, et al.
(författare)
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Simultaneous Fitting of Absorption Spectra and Their Second Derivatives for an Improved Analysis of Protein Infrared Spectra
- 2015
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Ingår i: Molecules. - : MDPI AG. - 1431-5157 .- 1420-3049. ; 20:7, s. 12599-12622
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Tidskriftsartikel (refereegranskat)abstract
- Infrared spectroscopy is a powerful tool in protein science due to its sensitivity to changes in secondary structure or conformation. In order to take advantage of the full power of infrared spectroscopy in structural studies of proteins, complex band contours, such as the amide I band, have to be decomposed into their main component bands, a process referred to as curve fitting. In this paper, we report on an improved curve fitting approach in which absorption spectra and second derivative spectra are fitted simultaneously. Our approach, which we name co-fitting, leads to a more reliable modelling of the experimental data because it uses more spectral information than the standard approach of fitting only the absorption spectrum. It also avoids that the fitting routine becomes trapped in local minima. We have tested the proposed approach using infrared absorption spectra of three mixed α/β proteins with different degrees of spectral overlap in the amide I region: ribonuclease A, pyruvate kinase, and aconitase.
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| 2. |
- Kumar, Saroj, et al.
(författare)
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Insights into Biochemical Alteration in Cancer-Associated Fibroblasts by using Novel Correlative Spectroscopy
- 2017
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Ingår i: ChemistryOpen. - : WILEY-V C H VERLAG GMBH. - 2191-1363. ; 6:1, s. 149-157
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Tidskriftsartikel (refereegranskat)abstract
- The microenvironment of a tumor changes chemically and morphologically during cancer progression. Cancer-stimulated fibroblasts promote tumor growth, however, the mechanism of the transition to a cancer-stimulated fibroblast remains elusive. Here, the multi-modal spectroscopic methods Fourier transform infrared imaging (FTIRI), X-ray absorption spectroscopy (XAS) and X-ray fluorescence imaging (XFI) are used to characterize molecular and atomic alterations that occur in cancerstimulated fibroblasts. In addition to chemical changes in lipids (olefinic and acyl chain) and protein aggregation observed with FTIRI, a new infrared biomarker for oxidative stress in stimulated fibroblasts is reported. Oxidative stress is observed to cause lipid peroxidation, which leads to the appearance of a new band at 1721 cm(-1), assigned to 4-hydroxynonenal. Complementary to FTIRI, XFI is well suited to determining atom concentrations and XAS can reveal the speciation of individual elements. XFI reveals increased concentrations of P, S, K, Ca within stimulated fibroblasts. Furthermore, XAS studies reveal alterations in the speciation of S and Ca in stimulated fibroblasts, which might provide insight into the mechanisms of cancer progression. Using XFI, not only is the concentration change of individual elements observed, but also the subcellular localization. This study demonstrates the wealth of biochemical information provided by a multi-modal imaging approach and highlights new avenues for future research into the microenvironment of breast tumors.
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