Analysis of Proteinaceous Components of the Organic Matrix of Endoskeletal Sclerites from the Alcyonarian Lobophytum crassum
Analysis of Proteinaceous Components of the Organic Matrix of Endoskeletal Sclerites from the Alcyonarian Lobophytum crassum
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Alcyonarian Lobophytum crassum 内骨骼骨片有机基质的蛋白质成分分析
DOI：
10.1007/s00223-005-0253-y
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发表时间：
2006
影响因子：
4.2
通讯作者：
T. Uehara
中科院分区：
文献类型：
--
作者：
Md. Mizanur Rahman;Y. Isa;A. Takemura;T. Uehara
alcyonarians的中胶层被大量微小的方解石硬石所占据。砂叶藻的硬晶石含有水溶性有机基质（占硬晶石重量的0.48%）和水不溶性部分（占硬晶石重量的1.15%）。对可溶性部分的蛋白质成分分析表明，天冬氨酸含量特别高，其次是丙氨酸、甘氨酸和谷氨酸。天冬氨酸、甘氨酸、丙氨酸和谷氨酸是不溶性部分中最丰富的残基。在这两种情况下，分数显示最高浓度的天冬氨酸从总蛋白质。在体外实验中，我们发现从钙质硬膜中提取的基质蛋白在其转化为钙质晶体形式之前诱导形成无定形碳酸钙。我们还展示了用作模板的方解石晶体的扫描电子显微图，以及这些晶体上印迹的蛋白质。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳显示两种基质在67和48 kDa的蛋白质部分。可溶基质显示另外两条微弱带。两个馏分在67 kDa的碳水化合物染色，表明该分子量的糖蛋白。新衍生的蛋白质序列进行了生物信息学分析，包括鉴定与其他酸性蛋白质的相似性。这些蛋白的鉴定强调了这些酸性蛋白的基本重要性，并进一步阐明了这些蛋白在生物钙化过程中的功能。
The mesoglea of alcyonarians is occupied by an abundance of minute calcitic sclerites. The sclerites of the alcyonarian Lobophytum crassum contain a water-soluble organic matrix comprising 0.48% of the sclerite weight and a water-insoluble fraction comprising 1.15% of the sclerite weight. Analysis of proteinaceous components in the soluble fraction shows a particularly high content of aspartic acid, followed by alanine, glycine, and glutamate. Aspartic acid, glycine, alanine, and glutamate are the most abundant residues in the insoluble fraction. In both cases, the fractions show the highest concentration of aspartic acid from the total proteins. In an in vitro assay, we show that the matrix proteins extracted from the calcitic sclerites induce the formation of amorphous calcium carbonate prior to its transformation into the calcitic crystalline form. We also show scanning electron micrographs of the rhombohedral calcite crystals used as template, the protein imprinted with these crystals. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of both matrices shows the protein fractions at 67 and 48 kDa. The soluble matrix shows two additional faint bands. Both fractions stain for a carbohydrate at 67 kDa, indicating a glycoprotein at this molecular weight. A newly derived protein sequence was subjected to bioinformatics analysis involving identification of similarities to other acidic proteins. The identification of these proteins in alcyonarian endoskeletal sclerites emphasizes the fundamental importance of such acidic proteins and sheds more light on the functions of these proteins in the processes of biocalcification.