The nacre protein perlucin nucleates growth of calcium carbonate crystals
The nacre protein perlucin nucleates growth of calcium carbonate crystals
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DOI：
10.1111/j.1365-2818.2003.01263.x
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发表时间：
2003-12-01
期刊：
影响因子：
--
通讯作者：
Fritz, M
中科院分区：
文献类型：
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作者：
Blank, S;Arnoldi, M;Fritz, M
利用原子力显微镜（AFM）在水溶液中研究了光滑鲍（Haliotis laevigata）天然珍珠层的微观结构和纯化珍珠层蛋白与碳酸钙晶体的纳米结构。这些调查控制扫描电子显微镜（SEM），光学显微镜（LM）和生化方法。对于与AFM和SEM的调查，珍珠层切割平行的文石片在这个生物聚合物/矿物复合材料。多层有机片层由甲壳素的核心与蛋白质层连接在两侧奠定之间的文石层组成的汇合文石片。在文石片层和蛋白质层之间出现分裂。原子力显微镜图像显示，一个蜂窝状结构的有机材料与直径的“蜂窝”等于文石片。结构的壁由细丝组成，这被认为是胶原蛋白。蜂窝状结构的平坦区域呈现出直径大于100 nm的孔。当在饱和碳酸钙溶液中孵育时，文石针状体以完美的垂直取向生长在蛋白质表面。用蛋白酶K处理后，没有检测到定向文石针的生长。直接原子力显微镜测量溶解和生长方解石晶体揭示了一个表面结构与直步骤的数量减少晶体生长。当纯化的珍珠层蛋白perlucin添加到生长溶液（过饱和碳酸钙溶液）的新层成核和步骤的数量增加。水溶性蛋白质的阴离子交换色谱显示约10种不同蛋白质的混合物。当将该混合物对饱和碳酸钙溶液和氯化钠透析时，碳酸钙晶体与perlucin一起沉淀，在上清液中留下其他蛋白质。因此，perlucin被证明是一种能够在方解石表面上使碳酸钙层成核的蛋白质，并且在氯化钠的存在下，作为晶内蛋白质掺入碳酸钙晶体中。
Atomic force microscopy (AFM) in aqueous solution was used to investigate native nacre of the marine snail Haliotis laevigata on the microscopic scale and the interaction of purified nacre proteins with calcium carbonate crystals on the nanoscopic scale. These investigations were controlled by scanning electron microscopy (SEM), light microscopy (LM) and biochemical methods. For investigations with AFM and SEM, nacre was cleaved parallel to the aragonite tablets in this biogenic polymer/mineral composite. Multilamellar organic sheets consisting of a core of chitin with layers of proteins attached on both sides lay between the aragonite layers consisting of confluent aragonite tablets. Cleavage appeared to occur between the aragonite tablet layer and the protein layer. AFM images revealed a honeycomb-like structure to the organic material with a diameter of the 'honeycombs' equalling that of the aragonite tablets. The walls of the structures consisted of filaments, which were suggested to be collagen. The flat regions of the honeycomb-like structures exhibited a hole with a diameter of more than 100 nm. When incubated in saturated calcium carbonate solution, aragonite needles with perfect vertical orientation grew on the proteinacous surface. After treatment with proteinase K, no growth of orientated aragonite needles was detected. Direct AFM measurements on dissolving and growing calcite crystals revealed a surface structure with straight steps the number of which decreased with crystal growth. When the purified nacre protein perlucin was added to the growth solution (a super-saturated calcium carbonate solution) new layers were nucleated and the number of steps increased. Anion exchange chromatography of the water-soluble proteins revealed a mixture of about 10 different proteins. When this mixture was dialysed against saturated calcium carbonate solution and sodium chloride, calcium carbonate crystals precipitated together with perlucin leaving the other proteins in the supernatant. Thus perlucin was shown to be a protein able to nucleate calcium carbonate layers on calcite surfaces, and in the presence of sodium chloride, is incorporated as an intracrystalline protein into calcium carbonate crystals.