Solid-State NMR Investigations of the Hydration and Molecular Dynamics of Collagen in Biological Tissue
Collagen is the most abundant protein in the human body and plays a central role in the biological function of various hard and soft tissues. With a unique amino acid composition and three dimensional structure, collagen confers tensile strength to bone, ligaments, tendon, cartilage, and other tissues. Solid-state NMR spectroscopy is a well-suited method to study intact biological tissues. In particular 13C NMR measurements under magic-angle spinning conditions provide insights into the structure, dynamics, and hydration of collagen in various biological tissues. Furthermore, quantitative 13C-31P distance measurements have helped characterizing the organic/inorganic interface of bone tissue. Hydration of the densely packed collagen fibrils has been found to significantly influence the dynamics of the molecular segments of collagen. In the NMR spectra, the water content of biological tissue has a profound impact on the resolution of the 13C NMR spectra of collagen. Furthermore, molecular order parameters, which report the amplitudes of the fluctuations of the bond vectors of the molecular segments of collagen with correlation times shorter than ~40 μs, provide a sensitive measure of the microscopic hydration properties of the protein in these tissues. Along with the analytical power of NMR spectroscopy, solid-state NMR investigations of the collagen dynamics provide a useful tool to assess the quality of de novo synthesized collagen also in tissue engineering studies. Altogether, collagen perfectly adapts to its molecular environment in hard and soft tissue to contribute to the basic strength, shape retention, and viscoelastic properties of biological matter.
KeywordsSolid-state NMR CPMAS REDOR DipShift INEPT 13C NMR 31P NMR H/D exchange Hydration Dynamics Order parameter Bone Cartilage Tissue engineering Fibrils Collagen
This research has been supported by the Deutsche Forschungsgemeinschaft (TRR-SFB 67, A06).
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