Natural-abundance 43Ca solid-state NMR spectroscopy of bone.
Natural-abundance 43Ca solid-state NMR spectroscopy of bone.
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DOI：
10.1021/ja101961x
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发表时间：
2010-08-25
影响因子：
15
通讯作者：
Ramamoorthy, Ayyalusamy
中科院分区：
文献类型：
--
作者：
Xu, Jiadi;Zhu, Peizhi;Gan, Zhehong;Sahar, Nadder;Tecklenburg, Mary;Morris, Michael D.;Kohn, David H.;Ramamoorthy, Ayyalusamy
有关骨中钙的配位环境的结构信息对于理解钙在骨形成、生物矿化和骨质疏松症等骨疾病中的作用非常有价值。虽然骨的高分辨率结构研究被认为是极具挑战性的，但对模型化合物和骨矿物质的NMR研究为骨结构提供了有价值的见解。特别是最近对模型化合物的43 Ca固体NMR实验的演示是该领域的一个重要进展。但由于~（43）Ca天然丰度低、灵敏度差，阻碍了~（43）Ca NMR的应用。在这项研究中，我们报告的第一个演示的自然丰度43钙魔角旋转（MAS）核磁共振实验骨，使用粉末状的牛皮质骨样品。通过与包括羟基磷灰石和碳酸化磷灰石的模型化合物的天然丰度的43 Ca NMR谱进行比较，分析牛皮质骨的43 Ca NMR谱。虽然羟基磷灰石和碳酸化磷灰石的43 Ca NMR谱非常相似，但它们与皮质骨的43 Ca NMR谱显著不同。拉曼光谱表明，骨中的钙环境更类似于碳酸化磷灰石而不是羟基磷灰石。对43 Ca NMR谱的仔细分析表明，皮质骨和10%碳酸化磷灰石的化学位移频率相似，但皮质骨的四极耦合常数大于模型化合物的测量值。此外，我们的研究结果表明，碳酸盐浓度的增加降低了所观察到的43 Ca化学位移频率。实验获得的43 Ca MAS光谱与模拟的比较揭示了碳酸化磷灰石中Ca-I：Ca-II位点的摩尔比为3：4，羟基磷灰石的摩尔比为2.3：3。对碳酸化磷灰石和骨蛋白骨钙素的混合物进行的2D三量子43 Ca MAS实验揭示了蛋白质结合和游离钙位点的存在，这与从蛋白质的X射线晶体结构开发的模型一致。
Structural information about the coordination environment of calcium present in bone is highly valuable in understanding the role of calcium in bone formation, biomineralization, and bone diseases like osteoporosis. While a high-resolution structural study on bone has been considered to be extremely challenging, NMR studies on model compounds and bone minerals have provided valuable insights into the structure of bone. Particularly, the recent demonstration of 43Ca solid-state NMR experiments on model compounds is an important advance in this field. However, application of 43Ca NMR is hampered due to the low natural-abundance and poor sensitivity of 43Ca. In this study, we report the first demonstration of natural-abundance 43Ca magic angle spinning (MAS) NMR experiments on bone, using powdered bovine cortical bone samples. 43Ca NMR spectra of bovine cortical bone are analyzed by comparing to the natural-abundance 43Ca NMR spectra of model compounds including hydroxyapatite and carbonated apatite. While 43Ca NMR spectra of hydroxyapatite and carbonated apatite are very similar, they significantly differ from that of cortical bone. Raman spectroscopy shows that the calcium environment in bone is more similar to carbonated apatite than hydroxyapatite. A close analysis of 43Ca NMR spectra reveals that the chemical shift frequencies of cortical bone and 10% carbonated apatite are similar but the quadrupole coupling constant of cortical bone is larger than that measured for model compounds. In addition, our results suggest that an increase in the carbonate concentration decreases the observed 43Ca chemical shift frequency. A comparison of experimentally obtained 43Ca MAS spectra with simulations reveal a 3:4 mole ratio of Ca-I:Ca-II sites in carbonated apatite and a 2.3:3 mole ratio for hydroxyapatite. 2D triple-quantum 43Ca MAS experiments performed on a mixture of carbonated apatite and the bone protein osteocalcin reveal the presence of protein-bound and free calcium sites, which is in agreement with a model developed from X-ray crystal structure of the protein.
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影响因子：
2.9
作者：
ARAMINI, JM;DRAKENBERG, T;VOGEL, HJ
通讯作者：
VOGEL, HJ
影响因子：
4.2
作者：
Kaflak-Hachulska, A;Samoson, A;Kolodziejski, W
通讯作者：
Kolodziejski, W
影响因子：
2.9
作者：
BRAUNLIN, WH;VOGEL, HJ;BENNICK, A
通讯作者：
BENNICK, A
影响因子：
4.2
作者：
Carden, A;Rajachar, RM;Kohn, DH
通讯作者：
Kohn, DH
影响因子：
56.9
作者：
Cho, GY;Wu, YT;Ackerman, JL
通讯作者：
Ackerman, JL