Calcium Binding in Enamel Fluid and Driving Force for Enamel Mineralization in the Secretory Stage of Amelogenesis
Calcium Binding in Enamel Fluid and Driving Force for Enamel Mineralization in the Secretory Stage of Amelogenesis
复制标题
釉质液中的钙结合和釉质生成分泌阶段釉质矿化的驱动力
作者：
E. Moreno;T. Aoba
在牙釉质形成的分泌阶段，猪牙釉质液中的大部分（约85%）钙似乎是以非离子形式存在。钙可能通过基质中存在的釉原蛋白的酶促降解衍生的肽或通过性质尚未确定的其他配体结合在流体中。通过用10 mmol/L CaCl 2溶液滴定一小份液体（50 μL），每次加入2 μL，测定假设复合物的表观解离常数。流体的初始组成通过分析确定。用特定离子和玻璃电极分别测定了滴定过程中的钙离子活度（Ca 2+）和pH值（沿着）。结合Ca的浓度[B]与（Ca 2+）的关系式为[B] = N（Ca 2+）/ {K +（Ca 2+）}，其中K为Ca-配体复合物的解离常数，N为每升液体中结合位点的数目。K和N的值通过非线性最小二乘程序获得。K值为7.47 × 10-5 mol/L，表明结合键相当弱，如果络合钙在釉质形成过程中充当储库和/或精细控制流体中的钙水平，则该特征似乎是有利的。通过模拟模型研究了钙离子总浓度、[Ca]T、磷离子总浓度、配体浓度和pH值对饱和度（DS）的影响。结果表明，对DS影响最大的因素是[Ca]T。本文根据现有的研究成果和文献报道，对釉质发生的一些物理化学方面进行了讨论。
A large portion (about 85%) of the calcium present in the fluid of porcine enamel in the secretory stage of amelogenesis appears to be in a non-ionic form. Calcium is probably bound in the fluid by peptides derived from the enzymatic degradation of the amelogenins present in the matrix or by other ligands of an as-yet-undetermined nature. The apparent dissociation constant of the hypothesized complex was determined by titration of a small aliquot of fluid (50 μL) with 10 mmol/L CaCl2 solution, adding 2 μL at a time. The initial composition of the fluid was determined analytically. The ionic calcium activity, (Ca 2+), and the pH value along the titration were determined by a specific ion and a glass electrode, respectively, with the same reference micro-electrode. The concentration of bound Ca, [B], was related to the (Ca2+) by the equation [B] = N(Ca2+)/ {K + (Ca2+)}, in which K is the dissociation constant of the Ca-ligand complex and N is the number of binding sites per liter of fluid. The values of K and N were obtained by a non-linear least-squares procedure. The value of K, 7.47 × 10-5 mol/L, indicates that the binding bond is rather weak, a feature that seems advantageous if complexed calcium acts as a reservoir and/or fine control of calcium levels in the fluid during enamel formation. The effects that the total concentration of calcium, [Ca]T, the total concentration of P, the concentration of ligand, and the pH value have on the degree of saturation (DS) were investigated by simulation models. It is concluded that the factor that most affects the DS is [Ca]T. Some physicochemical aspects of amelogenesis are discussed on the basis of present knowledge and the reported results.
牙釉质器官控制钙进入牙釉质发育的机制。
影响因子：
7.6
作者：
Crenshaw,MA;Takano,Y
通讯作者：
Takano,Y
发育中的牛牙釉质的有机基质与钙结合。
影响因子：
3
作者：
Drinkard,C;Gibson,L;Crenshaw,MA;Bawden,JW
通讯作者：
Bawden,JW