Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin 53706, USA.
J Am Chem Soc. 2010 May 12;132(18):6329-34. doi: 10.1021/ja909735y.
Proteins play a major role in the formation of all biominerals. In mollusk shell nacre, complex mixtures and assemblies of proteins and polysaccharides were shown to induce aragonite formation, rather than the thermodynamically favored calcite (both aragonite and calcite are CaCO(3) polymorphs). Here we used N16N, a single 30 amino acid-protein fragment originally inspired by the mineral binding site of N16, a protein in the nacre layer of the Japanese pearl oysters (Pinctada fucata). In a calcite growth solution this short peptide induces in vitro biomineralization. This model biomineral was analyzed using X-ray PhotoElectron Emission spectroMicroscopy (X-PEEM) and found to be strikingly similar to natural nacre: lamellar aragonite with interspersed N16N layers. This and other findings combined suggest a hypothetical scenario in which in vivo three proteins (N16, Pif80, and Pif97) and a polysaccharide (chitin) work in concert to form lamellar nacre.
蛋白质在所有生物矿化的形成中都起着重要作用。在软体动物贝壳珍珠层中，复杂的蛋白质和多糖混合物和组装被证明可以诱导方解石的形成，而不是热力学上有利的文石（方解石和文石都是 CaCO3 的多晶型物）。在这里，我们使用了 N16N，这是一个最初受珍珠层中 N16 蛋白的矿物结合位点启发的 30 个氨基酸的单一蛋白片段。在方解石生长溶液中，这种短肽会诱导体外生物矿化。使用 X 射线光电子发射光谱显微镜 (X-PEEM) 分析了这种模型生物矿化物，发现它与天然珍珠层非常相似：层状文石，其中穿插着 N16N 层。这些和其他发现结合在一起，提出了一个假设的情景，即在体内三种蛋白质（N16、Pif80 和 Pif97）和一种多糖（几丁质）协同作用形成层状珍珠层。
