First-principles calculations of Raman vibrational modes in the fingerprint region for connective tissue

Abstract

Vibrational spectroscopy has been widely employed to unravel the physical-chemical properties of biological systems. Due to its high sensitivity to monitoring real time "" changes, Raman spectroscopy has been successfully employed, e.g., in biomedicine, metabolomics, and biomedical engineering. The interpretation of Raman spectra in these cases is based on the isolated macromolecules constituent vibrational assignment. Due to this, probing the anharmonic or the mutual interactions among specific moieties/side chains is a challenge. We present a complete vibrational modes calculation for connective tissue in the fingerprint region (800 - 1800 cm) using first-principles density functional theory. Our calculations accounted for the inherent complexity of the spectral features of this region and useful spectral markers for biological processes were unambiguously identified. Our results indicated that important spectral features correlated to molecular characteristics have been ignored in the current tissue spectral bands assignments. In particular, we found that the presence of confined water is mainly responsible for the observed spectral complexity.

Raman spectroscopy reveals age- and sex-related differences in cortical bone from people with osteoarthritis

“…7 A. The strongest band components at 1662 and 1675 cm −1 represent α-helices 21 , 25 , 27 , while the bands at 1634 and 1690 cm −1 represent random coiled structures 11 , 30 , 34 . The 1660 cm −1 band has also been assigned to pyridinoline (non-reducible) cross-linking, amide I C=C and C=O stretching in collagen, CH 2 /CH 3 stretching and deformation, NH 2 stretching and deformation of lipids and collagen 9 , 20 , 24 , 26 , 35 .…”

“…Differences between the samples are seen particularly in the relative band intensities of the PO 4 3− bands (~ 959 and 500–600 cm −1 ). Other differences occur in the complex amide I vibrational mode (1620–1700 cm −1 ), due to C=O stretching vibration of the N–C=O functional groups in the amide backbone), and amide III mode (1200–1300 cm −1 , representing the NH 2 deformations) 27 – 30 . Differences also occur in the CH 2 and CH 3 deformation modes (δ(C–H) ~ 1440–1460 cm −1 ) and the CH 2 and CH 3 stretching modes (ν(C-H) ~ 2800–3100 cm −1 ).…”

“…Many of the phosphate and monohydrogen phosphate modes overlap extensively with those of the carbonate 31 and collagen 30 vibrational modes, making it difficult to accurately assign the individual bands. Changes in relative amounts of random coil and helix structures have been measured from resolved band component intensities for the amide III band at 1243 cm −1 and 1273 cm −1 , respectively 11 , 25 , 26 , 29 , 30 , 32 , and from components in the amide I band (1700–1600 cm −1 ) 33 . The averaged amide I spectral region for each of the 18 samples are shown in overlaid format in Fig.…”

“…7D. The 1301 cm −1 component has been assigned to deformations of phospholipids and of -CH 3 and -CH 2 groups in collagen and lipids 3,29,30 . The 1246 cm −1 component arises from random coil structures and the 1273 cm −1 component is assigned to α-helix structures.…”

Ftir Spectroscopic Trends and Dna Damage in Rabbit Lens Due to Long Run of Tamoxifen Treatment

“…Protein-water interactions are known to play a critical role in the function of several biological systems and macromolecules including collagen in tissues. Small changes in structure and dynamical behavior of water molecules at the peptide-water interface can effectively change both the structure and dynamics of the protein function [16]. By calculating the intensity ratio between amide I and amide II for control lens tissue, it was 2.23 that high to characterize the normal lens tissue.…”