Mroue Kamal H, Nishiyama Yusuke, Kumar Pandey Manoj, Gong Bo, McNerny Erin, Kohn David H, Morris Michael D, Ramamoorthy Ayyalusamy
1] Department of Biophysics, University of Michigan, Ann Arbor, Michigan, 48109-1055, United States [2] Department of Chemistry, University of Michigan, Ann Arbor, Michigan, 48109-1055, United States.
1] JEOL RESONANCE Inc., Musashino, Akishima, Tokyo 196-8558, Japan [2] RIKEN CLST-JEOL Collaboration Center, Tsurumi, Yokohama, Kanagawa 230-0045, Japan.
Sci Rep. 2015 Jul 8;5:11991. doi: 10.1038/srep11991.
While obtaining high-resolution structural details from bone is highly important to better understand its mechanical strength and the effects of aging and disease on bone ultrastructure, it has been a major challenge to do so with existing biophysical techniques. Though solid-state NMR spectroscopy has the potential to reveal the structural details of bone, it suffers from poor spectral resolution and sensitivity. Nonetheless, recent developments in magic angle spinning (MAS) NMR technology have made it possible to spin solid samples up to 110 kHz frequency. With such remarkable capabilities, (1)H-detected NMR experiments that have traditionally been challenging on rigid solids can now be implemented. Here, we report the first application of multidimensional (1)H-detected NMR measurements on bone under ultrafast MAS conditions to provide atomistic-level elucidation of the complex heterogeneous structure of bone. Our investigations demonstrate that two-dimensional (1)H/(1)H chemical shift correlation spectra for bone are obtainable using fp-RFDR (finite-pulse radio-frequency-driven dipolar recoupling) pulse sequence under ultrafast MAS. Our results infer that water exhibits distinct (1)H-(1)H dipolar coupling networks with the backbone and side-chain regions in collagen. These results show the promising potential of proton-detected ultrafast MAS NMR for monitoring structural and dynamic changes caused by mechanical loading and disease in bone.
虽然从骨骼中获取高分辨率的结构细节对于更好地理解其机械强度以及衰老和疾病对骨骼超微结构的影响非常重要，但利用现有的生物物理技术来实现这一点一直是一项重大挑战。尽管固态核磁共振光谱有揭示骨骼结构细节的潜力，但它存在光谱分辨率和灵敏度较差的问题。尽管如此，魔角旋转（MAS）核磁共振技术的最新进展使得以高达110 kHz的频率旋转固体样品成为可能。凭借如此卓越的能力，传统上在刚性固体上具有挑战性的（1）H检测核磁共振实验现在可以实施了。在此，我们报告了在超快MAS条件下对骨骼进行多维（1）H检测核磁共振测量的首次应用，以提供对骨骼复杂异质结构的原子水平阐释。我们的研究表明，在超快MAS下使用fp-RFDR（有限脉冲射频驱动偶极重耦合）脉冲序列可获得骨骼的二维（1）H/（1）H化学位移相关谱。我们的结果推断，水在胶原蛋白的主链和侧链区域表现出独特的（1）H-（1）H偶极耦合网络。这些结果显示了质子检测超快MAS核磁共振在监测骨骼中机械负荷和疾病引起的结构和动态变化方面的广阔前景。
