Premium
High pressure Raman study of type‐I collagen
Author(s) -
Paschou Amalia Maria,
Katsikini Maria,
Christofilos Dimitrios,
Arvanitidis John,
Ves Sotirios
Publication year - 2018
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.14506
Subject(s) - raman spectroscopy , softening , molecule , hydrogen bond , materials science , denaturation (fissile materials) , strain (injury) , amide , chemistry , crystallography , analytical chemistry (journal) , composite material , chromatography , organic chemistry , optics , medicine , physics , nuclear chemistry
The high pressure response of type‐I collagen from bovine Achilles tendon is investigated with micro‐Raman spectroscopy. Fluorinert™ and methanol‐ethanol mixtures were used as pressure transmitting media (PTM) in a diamond anvil cell. The Raman spectrum of collagen is dominated by three bands centred at approximately 1450, 1660 and 2930 cm −1 , attributed to C–H deformation, C=O stretching of the peptide bond (amide‐I band) and C–H stretching modes respectively. Upon pressure increase, using Fluorinert™ as PTM, a shift towards higher frequencies of the C–H stretching and deformation peaks is observed. Contrary, the amide‐I band peaks are shifted to lower frequencies with moderate pressure slopes. On the other hand, when using the alcohol mixture as PTM, the amide‐I band exhibits more pronounced C=O bond softening, deduced from the shift to lower frequencies, suggesting a strengthening of the hydrogen bonds between glycine and proline residues of different collagen chains due to the presence of the polar alcohol molecules. Furthermore, some of the peaks exhibit abrupt changes in their pressure slopes at approximately 2 GPa, implying a variation in the compressibility of the collagen fibres. This could be attributed to a pitch change from 10/3 to 7/2, sliding of the tropocollagen molecules, twisting variation at the molecular level and/or elimination of the D‐gaps induced by kink compression. All spectral changes are reversible upon pressure release, which indicates that denaturation has not taken place. Finally, a minor lipid phase contamination was detected in some sample spots. Its pressure response is also monitored.