Inhibition of hydroxyapatite growth by casein, a potential salivary phosphoprotein homologue.
Inhibition of hydroxyapatite growth by casein, a potential salivary phosphoprotein homologue.
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酪蛋白（一种潜在的唾液磷蛋白同系物）抑制羟基磷灰石生长。
DOI：
10.1111/eos.12196
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Tagami J.
中科院分区：
文献类型：
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作者：
Romero MJ;Nakashima S;Nikaido T;Ichinose S;Sadr A;Tagami J.
唾液磷蛋白在牙齿矿物质调节中是必不可少的，但在体外常常被忽视。本研究旨在评价酪蛋白作为一种唾液磷蛋白同系物，对羟基磷灰石（HA）在牙齿表面沉积和生长的影响。使用晶种晶体系统定量羟基磷灰石生长。将含有HA粉末和0、10、20、50或100μg ml− 1酪蛋白或100 μ g ml − 1脱磷酸化酪蛋白（D酪蛋白）的人工唾液（AS）在37°C，pH 7.2下孵育0-8 h。使用原子吸收光谱法（AAS）测量钙浓度。使用场发射扫描电子显微镜（FE-SEM）和透射电子显微镜（TEM）结合选区电子衍射（SAED）检查在相似条件下孵育7 d的牛牙釉质和牙本质块上HA的表面沉淀。使用改良的Lowry测定法和zeta电位测量法评估酪蛋白吸附。AAS结果显示钙消耗的浓度依赖性抑制。当不存在酪蛋白时发生羟基磷灰石沉淀，而在含酪蛋白组中HA沉淀明显被完全抑制。吸附数据表明，随着酪蛋白浓度的增加，zeta电位负性逐渐增加，亲和常数与富含脯氨酸的蛋白质相似（Langmuir模型）。酪蛋白主要通过磷酸盐结合到HA活性位点来抑制HA的沉积和生长，表明其在体外作为矿物质调节唾液磷蛋白同系物的潜力。
Salivary phosphoproteins are essential in tooth mineral regulation but are often overlooked in vitro. This study aimed to evaluate the effect of casein, as a salivary phosphoprotein homologue, on the deposition and growth of hydroxyapatite (HA) on tooth surfaces. Hydroxyapatite growth was quantified using seeded crystal systems. Artificial saliva (AS) containing HA powder and 0, 10, 20, 50, or 100μg ml−1of casein, or 100μg ml−1of dephosphorylated casein (Dcasein), was incubated for 0–8 h at 37°C, pH 7.2. Calcium concentrations were measured using atomic absorption spectroscopy (AAS). Surface precipitation of HA on bovine enamel and dentine blocks, incubated in similar conditions for 7 d, was examined using field emission scanning electron microscopy (FE‐SEM) and transmission electron microscopy (TEM) with selected area electron diffraction (SAED). Casein adsorption was assessed using modified Lowry assays and zeta‐potential measurements. The AAS results revealed a concentration‐dependent inhibition of calcium consumption. Hydroxyapatite precipitation occurred when no casein was present, whereas precipitation of HA was apparently completely inhibited in casein‐containing groups. Adsorption data demonstrated increasingly negative zeta‐potential with increased casein concentration and an affinity constant similar to proline‐rich proteins with Langmuir modelling. Casein inhibited the deposition and growth of HA primarily through the binding of esterized phosphate to HA active sites, indicating its potential as a mineral‐regulating salivary phosphoprotein homologue in vitro.