Structural Characterization of Bone by Solid-State NMR Spectroscopy

Thanks to NIH funding support

"Dehydration-Controlled Structural Changes in Intact Cortical Bone by Solid-State NMR Spectroscopy"

    We have been investigating the dehydration-induced conformational changes in intact bones using 13C and 1H magic-angle-spinning (MAS) NMR experiments:

Carbon-13 Ramp-CP MAS ssNMR spectra of intact fresh and dehydrated 60 mg bovine cortical bone samples. Both spectra were collected on a Varian VNMRS 600 MHz NMR spectrometer using a 4 mm double-resonance MAS probe with a 2 ms ramp cross-polarization under 10 kHz spinning speed. The bone samples were shaped to a 2.5 × 2.5 × 12 mm size and inserted into 4 mm zirconia MAS rotors.

              "Natural-Abundance 43Ca Solid-State NMR Spectroscopy of Bone"

   We have been analyzing the calcium coordination environment of bovine cortical bone and model compounds for bone mineral, including hydroxyapatite and carbonated apatite, using 43Ca 1D MAS and 2D 3Q-MAS NMR experiments:

Two-dimensional 3Q-MAS 43Ca ssNMR spectrum that correlates the 43Ca chemical shift and a triple-quantum frequency of 43Ca-enriched carbonated apatite powder sample containing osteocalcin protein at room temperature. The spectrum was collected on a Bruker 833 MHz NMR spectrometer using a single-channel 4 mm MAS probe tuned to 55.8 MHz, with a 10 kHz spinning speed.

"Insights Into the Dehydration of Cartilage via Solid-State NMR Spectroscopy" 
    We have been investigating the structure and dynamics of polymeric molecules of articular cartilage using time-resolved solid-state NMR spectroscopy during dehydration. Our results reveal that dehydration reduces the mobility of collagen amino acid residues and carbon sugar ring structures in glycosaminoglycans but has no effect on the trans-Xaa-Pro conformation. Equally interestingly, our results demonstrate that the dehydration effects are reversible, and the molecular structure and mobility are restored upon rehydration.

A bovine articular cartilage (A) and its molecular-level representation (B). Carbon-13 ssNMR spectra of cartilage obtained using Ramp-CP (blue) and RINEPT (red) pulse sequences under 10 kHz MAS at 25 °C. Both spectra were collected on a Varian VNMRS 600 MHz NMR spectrometer using a 4 mm double resonance MAS probe. 

Our Bone NMR Publications:

  • McElderry JP, Zhu P, Mroue KH, Xu J, Pavan B, Fang M, Zhao G, McNerny E, Kohn DH, Franceschi RT, Banaszak-Holl MM, Tecklenberg MMJ, Ramamoorthy A and Morris MD. Crystallinity and compositional changes in carbonated apatite. Evidence from 31P solid state NMR, Raman and AFM analysis. J Solid State Chem. (in press)
  • Mroue KH, MacKinnon N, Xu J, Zhu P, McNerny E, Kohn DH, Morris MD, Ramamoorthy A. High-Resolution Structural Insights into Bone: A Solid-State NMR Relaxation Study Utilizing Paramagnetic Doping. J. Phys. Chem. B 116 (2012) 11656−11661.
  • Xu JD, Zhu PZ, Morris MD, Ramamoorthy A. Solid-State NMR Spectroscopy Provides Atomic-Level Insights Into the Dehydration of Cartilage. J. Phys. Chem. B 115 (2011) 99489954.
  • Xu J, Zhu P, Gan Z, Sahar N, Tecklenburg M, Morris MD, Kohn DH, Ramamoorthy A. Natural-Abundance 43Ca Solid-State NMR Spectroscopy of Bone. J. Am. Chem. Soc. 132 (2010) 1150411509.
  • Zhu PZ, Xu JD, Sahar N, Morris MD, Kohn DH, Ramamoorthy A. Time-Resolved Dehydration-induced Structural Changes in an Intact Bovine Cortical Bone Revealed by Solid-State NMR Spectroscopy. J. Am. Chem. Soc. 131 (2009) 1706417065.