- 學位論文
固態核磁共振於生物礦化中有機—無機作用力之研究
Solid-State NMR Studies of Organic–Inorganic Interactions in Biomineralization
摘要
生物礦化為生物體內產生高階層式結構礦物的過程。由於生物礦化為二個不相像的有機分子及無機礦物交互作用下的複雜結果，故這類有機�無機混雜系統的結構資訊非常難以得到，而其機制亦無從回答。本論文先研發出數種固態核磁共振的技術（第三章），包含同核磁偶極作用力回耦、異核磁偶極作用力回耦及胜肽扭轉角的測定等等。這些技術經由標準樣品測試後，隨即應用在數種特別設計的磷酸鈣礦化模型系統（第四章），以得到重要的結構資訊。 第一個模型系統係以簡單高溫水熱法研究在生物分子（谷氨酸）的存在下之磷酸鈣的相轉變過程（第四章第一節）。基於實驗結果，我們發現整個相轉變的過程遵循溶解－再生成之機制；且此相轉變過程會因谷氨酸之存在而加速。此加速的效應乃因谷氨酸能破壞磷酸鈣晶體的表面水層，幫助離子沉積生長所致。第四章第二及三節則為利用固態核磁共振技術解出磷酸八鈣內嵌琥珀酸之分子模型。由先前的研究，此有機�無機錯合物可能為粒腺體中生物礦化中間體的成份之一。由於在嵌入琥珀酸後，磷酸八鈣的穩定性較未嵌入者為高，故由此判定磷酸八鈣晶體內部的水層在相轉變的過程中扮演極重要的角色。第四章第四節則利用二維光譜的訊號強度，推斷胜肽和晶體表面作用時，其氨基酸的動力學變化。實驗結果顯示胜肽中所含的賴氨酸在樣品加水前後之動力學變化較小且離表面較近，故由此推測該氨基酸極有可能為胜肽和礦物表面的作用處。由於賴氨酸的側鏈帶有正電，推論胜肽和礦物表面的作用力除了胜肽側鏈羧基所帶的負電會和晶體表面的鈣離子作用外，胜肽本身所帶的正電亦對晶體的辨認有一定的貢獻。
並列摘要
Biomineralization refers to a biological process describing the formation of highly ordered inorganic materials with hierarchical structures in living organisms. Because a biomineralization process typically involves the interfacial interactions of two dissimilar nanophases, it is extremely challenging to obtain the structural information of such organic/inorganic hybrid systems at the molecular level. Therefore, the mechanisms in biomineralization remain largely unknown. In this work, we have developed several solid-state NMR techniques, including homonuclear dipole–dipole recoupling, heteronuclear dipole–dipole recoupling, and torsion angle determination (Chapter 3). These techniques are subsequently employed to extract valuable information, that would be difficult to obtain otherwise, in specific in vitro model systems of calcium phosphate The first model system describes a phase transformation pathway of calcium phosphate in the presence of glutamic acid under hydrothermal condition (Chapter 4.1). On the basis of experimental data, it is suggested that the transformation is via the dissolution-reprecipitation pathway, which is facilitated in the presence of glutamic acid. This effect is rationalized by the disruption of the water layer that bound on the crystal surface. Chapter 4.2 & 4.3 have utilized solid-state NMR spectroscopy to resolve the molecular structure of octacalcium phosphate incorporated with succinate (OCPS), which is hypothesized as an important model compound of the mineral granules found in mitochondria. Based on the fact that OCPS is more stable than octacalcium phosphate (OCP) under hydrolysis conditions, it is concluded that the hydration layer of OCP is playing the key role in the structural transformation of OCP. Chapter 4.4 discusses the structural dynamics near the N-terminus fragment of statherin (SN15) upon binding on HAp, which are extracted from the spectral analyses of two-dimensional 13C–13C correlation spectra. It has been found that the residue K6 is very close to the mineral surface and its molecular motion, if any, is relatively insensitive to the hydration level of the sample. Consequently, K6 is most likely one of the anchoring sites for SN15 bound on HAp. This result infers that positive charges of polypeptides may also contribute to the peptide–mineral recognition process.
並列關鍵字
Biomineralization ； Solid-state NMR ； Calcium phosphate ； Dipolar recoupling ； Hydroxyapatite ； Octacalcium phosphate ； HAp ； OCP ； MAS ； Water layer參考文獻
延伸閱讀
- 高憲明（2001）。應用固態核磁共振方法在分子篩觸媒材料的結構鑑定。化學，59(1)，71-75。https://doi.org/10.6623/chem.2001009
- 劉婉華、陳守一（1995）。核磁共振光譜技術在非離子性界面活性劑分析上的應用。化學，53(2)，163-184。https://doi.org/10.6623/chem.1995015
- 諸柏仁（2001）。固態核磁共振於材料的研究應用。化學，59(1)，61-62。https://doi.org/10.6623/chem.2001007
- 蘇佳偉（2006）。以固態核磁共振光譜探討層狀金屬鈷氧化物之電子結構〔碩士論文，國立暨南國際大學〕。華藝線上圖書館。https://doi.org/10.6837/NCNU.2006.00003
- Yeh, W. T. (2006). Conformational Investigation of PSGL-1: CD and NMR Spectroscopic Studies [master's thesis, National Taiwan University]. Airiti Library. https://doi.org/10.6342/NTU.2006.10510