Gotliv Bat-Ami, Robach Joshua S, Veis Arthur
Department of cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303E Chicago Avenue, Chicago, IL 60611-3008, USA.
J Struct Biol. 2006 Nov;156(2):320-33. doi: 10.1016/j.jsb.2006.02.005. Epub 2006 Mar 9.
The dentin layer of the tooth is a complex mineralized tissue traversed by a closely packed system of tubules. Each tubule is surrounded by highly mineralized tissue referred to as peritubular dentin (PTD). The remaining mineralized collagen network between the tubules is the intertubular dentin (ITD). A TOF-SIMS analysis of the PTD constituents has been used to compare the PTD to the ITD. The PTD differs from the ITD not only in the degree of mineralization but also in the amount and nature of the mineral elements and amino acids. The organic matrix of the PTD consists of a unique collagen free assembly of proteins rich in glutamic acid, where the ITD organic matrix is collagen-rich and Asp-rich. The apparent concentration of organic fragment ions observed in the PTD in the TOF-SIMS negative ion mode was much higher than expected. The PTD was found to be rich in Ca2+, Na+, Mg2+, and K+. The amount of Mg2+ and K+ in the PTD was significantly reduced after deproteination, while Ca2+ and Na+ were still accumulated in the PTD. This implies that Mg2+ and K+ are mainly associated with the organic matrix rather than with the mineral of the PTD.
牙齿的牙本质层是一种复杂的矿化组织，由紧密排列的小管系统贯穿其中。每个小管被称为管周牙本质（PTD）的高度矿化组织所包围。小管之间剩余的矿化胶原网络是管间牙本质（ITD）。已使用对PTD成分的飞行时间二次离子质谱（TOF-SIMS）分析来比较PTD和ITD。PTD与ITD的不同之处不仅在于矿化程度，还在于矿质元素和氨基酸的数量及性质。PTD的有机基质由富含谷氨酸的独特无胶原蛋白质组装体组成，而ITD的有机基质富含胶原和天冬氨酸。在TOF-SIMS负离子模式下，在PTD中观察到的有机碎片离子的表观浓度远高于预期。发现PTD富含Ca2+、Na+、Mg2+和K+。脱蛋白后，PTD中Mg2+和K+的量显著减少，而Ca2+和Na+仍在PTD中积累。这意味着Mg2+和K+主要与有机基质相关，而非与PTD的矿物质相关。
